JAS - Devt of Mammalian GI Tract

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R. K. Buddington and P. T. Sangildrole of diet in early life

Development of the mammalian gastrointestinal tract, the resident microbiota, and the

published online January 14, 2011 J ANIM SCI

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Running head: GI development, bacteria, and diet

Development of the mammalian gastrointestinal tract, the resident

microbiota, and the role of diet in early life 1

R. K. Buddington* 2 and P.T. Sangild

*Dept Health and Sport Science, University of Memphis, Memphis, TN 38152, USA

Dept Human Nutrition, University of Copenhagen, DK-1958 Frederiksberg C, Denmark

1 Based on a presentation at the Companion Animals Symposium, Microbes and Health, at

the joint annual meeting of the American Dairy Science Association, Poultry Science

Association, Asociacin Mexicana de Produccin Animal, Canadian Society of Animal

Science, and American Society of Animal Science, July 11-15, 2010, Denver, CO.

2 Corresponding author: [email protected]

Published Online First on January 14, 2011 as doi:10.2527/jas.2010-3705by guest on February 1, 2012 jas.fass.orgDownloaded from
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ABSTRACT: Mammalian gastrointestinal (GI) development is guided by genetic determinants

established during the evolution of mammals and matched to the natural diet and environment.

Co-evolution of the host GI tract (GIT) and the resident bacteria has resulted in commensal

relationships that are species and even individual specific. The interactions between the host and

the GI bacteria are two-way and of particular importance during the neonatal period when the

GIT needs to rapidly adapt to the external environment, begin processing of oral foods, and

acquire the ability to differentiate between and react appropriately to colonizing commensal and

potentially pathogenic bacteria. During this crucial period of life the patterns of gene expression

that determine GI structural and functional development are modulated by the bacteriacolonizing the previously sterile GIT of fetuses. The types and amounts of dietary inputs after

birth influence GI development, species composition and metabolic characteristics of the resident

bacteria, and the interactions that occur between the bacteria and the host. This review provides

overviews of the age-related changes inGIT functions, the resident bacteria, and diet, and

describes how interactions among these three factors influence the health and nutrition of

neonates and can have lifelong consequences. Necrotizing enterocolitis is a common GI

inflammatory disorder in preterm infants and is provided as an example of when the interactions

go awry. Other enteric diseases are common in all newborn mammals and an understanding of

the above interactions will enhance efforts to support neonatal health for infants and farm and

companion animals.

Keywords: bacteria, diet, development, gastrointestinal, mammal, ontogeny

INTRODUCTION

We must cultivate our garden from Candide (Voltaire, 1759). When Candide left



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sheltered castle life and entered into the external world he faced challenges and hardships and his

survival was dependent on discriminating between good and evil. Similarly, when the fetus

emerges from the shelter of the womb the immature gastrointestinal tract must adapt rapidly to

oral feeding, the challenges of extrauterine life, and to cultivating the garden of colonizing

bacteria.

Complex interactions have evolved between the mammalian host and the gastrointestinal

(GI ) microbiota (Ley et al., 2008). Apparently, the extreme costs that would be imposed on the

host by trying to maintain a sterile GI tract ( GIT ) are outweighed by the benefits of instead

establishing commensal relationships with bacteria that provide health and nutritional benefitsand pose little or no risk to the host. Hence, the GIT has come to accept the presence of

numerous species of bacteria at densities such that GI bacterial cells shortly after birth

outnumber those of the host by about 10-fold.

Much like the challenges faced by Candide, after birth the GIT must establish and

maintain a delicate balance between the recognition and exclusion of pathogens and the tolerance

of commensal bacteria. The GI disorder necrotizing enterocolitis ( NEC ) is exemplary of the

consequences when the balance between exclusion and tolerance is disrupted and when members

of the commensal bacteria trigger excessive inflammatory responses, thereby compromising

health of the neonate (Claud, 2009).

The interactions among the GIT, the resident microbiota and diet begin at birth when the

sterile epithelium of the GIT first encounters the colonizing bacteria and begins processing the

first meals. During this critical period of life genetic determinants of immune responses play a

central role in the recognition of and the responses of the developing GIT to the colonizing

bacteria. Although dietary inputs influence postnatal development of the GIT, less understood



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are how dietary inputs have the potential to influence the interactions between the GI epithelium

and the colonizing bacteria. The contrasting responses of the neonatal GIT and the resident

bacteria among infants fed breast milk and those fed formula (Hanson, 2007; Penders et al.,

2007) highlight how interactions among the genetic determinants of GI characteristics, the

resident bacteria, and dietary inputs must be considered together to understand postnatal GI

development in health and disease.

The objective of our review is to acquaint readers with the responses of the neonatal

mammalian GIT to the bacteria that colonize and become established, and how diet is an

important factor in those interactions. We first provide readers with a general understanding of mammalian GI development, the postnatal changes in the resident bacteria, and shifts in dietary

inputs. Although the described changes are shared among different mammalian species, there

are differences in the timing and specifics of the developmental events. Next, we describe the

interactions that exist among genetic determinants of GI structure and functions, the resident

bacteria, and diet. A subsequent section uses NEC, often observed in preterm infants, as an

example to describe the consequences when the interactions among GI development, the resident

bacteria, and diet go awry. We conclude by discussing some dietary strategies to improve health

by optimizing the interactions between the developing GIT and the resident microbiota.

DEVELOPMENT OF THE GIT

The GIT represents a critical and expansive interface between the external environment

and the host. Organogenesis and maturation of the GIT during prenatal life prepares the fetus for

the transition at birth from the sterile intrauterine environment and reliance on placental nutrition

to the immediate and dramatic changes in the functional demands placed on the GIT by exposure

to the contaminated environment, digesting food, and other challenges of extrauterine life. The



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importance of the GIT being functional at the time of birth is evident by the complications of

preterm birth and the consequences of immature GI functions. A notable example is the

increased risk of NEC among preterm infants, as discussed subsequently.

During prenatal development the GIT acquires the capacities to: 1) digest food; 2) defend

against pathogens; 3)contribute to osmoregulation; 4) secrete hormones and other signaling

molecules that regulate the GIT and other host systems, and 5) detoxify and eliminate toxins

produced by metabolism and acquired from the external environment. Some of the GIT

capabilities that develop prenatally are vital for the fetus to process the large volumes of

swallowed amniotic fluid; up to 750 ml per day by human fetuses (Pritchard 1966). At term theGIT is able to process milk, respond to bacterial colonization, and tolerate extrauterine

environmental conditions. However, the specific structural and functional characteristics of the

GIT at birth vary among species. This is exemplified by comparisons of the GIT among

newborns of altricial and precocial species with different adult feeding habits and from different

environments (Stevens and Hume, 1995).

The changes in the GIT associated with weaning can be accelerated by advancing the

transition from milk to the adult diet, as well as delayed, but not prevented by extending

suckling. This highlights how the patterns and trajectories of GI development are established by

genetic determinants (hard wired). Yet, the programmed series of events is responsive to

dietary inputs (Drozdowski et al., 2010), to environmental conditions (Bailey and Halversen,

2006), and are capable of some flexibility to allow the developing GIT to adapt to existing

conditions (Lebenthal and Lebenthal, 1999). There is also evidence for critical period

programming of GI characteristics whereby dietary inputs early in life can induce epigenetic

changes that persist past the period of exposure and can last for an individuals lifetime



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(Drozdowski et al., 2010). This includes early programming of the GI immune system by the

colonizing bacteria and environmental antigens (Mulder et al., 2009).

Digestion. At term the GIT is adapted for and ready to process the first food, which for

most mammals is colostrum (Drozdowski et al., 1010). The immature digestive functions of

preterm infants are considered to contribute to the increased risk of NEC (reviewed by Claud,

2009) and are why total parenteral nutrition ( TPN ) is used to meet nutrient and energy needs

until the GIT develops adequate capacities to process food.

Suckling mammals have minimal capacities to adaptively modulate digestive processes

in response to changes in diet composition (Buddington, 1994) and do not acquire the abilities to process the adult diet until just prior to weaning (Drozdowski et al., 2010). When neonates are

not fed breast milk, diarrhea can result when the alternate diet includes ingredients, such as

sucrose, for which there is inadequate expression of sucrase. .

Defense. The GI immune system provides a comprehensive, multi-layered defense

(Winkler et al 2007). Much like a gardener, the GI immune system is able to differentiate among

the numerous types of GI bacteria that represent a threat and those that should be tolerated and

contributes to the selection of an assemblage of commensal bacteria (Ogra, 2010). This is the

culmination of co-evolution between the resident bacteria and the innate and adaptive

components of the GI immune system and is dependent on a diversity of extracellular Toll-like

receptors ( TLR ) and intracellular nucleotide-binding oligomerization domain ( NOD ) receptors

(Richardson et al., 2010; Shibolet and Podolsky, 2007). Aberrant and excessive reactions of the

GI immune system to commensal bacteria and other antigens in the GIT causes inflammation

and has been associated with several pathologies, including NEC in preterm infants and

inflammatory bowel disease, celiac disease, and various food allergies in children and adults.



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Conversely, inadequate recognition or responses to pathogens pose obvious health risks.

GI immune functions develop prenatally and at term are capable of recognizing and

responding to pathogens, including bacterial DNA motifs and vaccines (Lacroix-Lamonde et al.,

2009). Additional development and maturation occur after birth and the several phases described

for the porcine GI immune system (Bailey and Halverson, 2006) are relevant to most mammals.

The innate GI defenses include secretions of acid, antimicrobial peptides, lysozyme,

mucous, the tight junctions that link epithelial cells and provide a physical barrier, activated

defense cells (e.g., macrophages, neutrophils), motility, and glycoconjugates that function as

receptor mimics (Eckmann, 2006). These are supplemented at birth by the transient ability of theenterocytes of neonates to absorb intact and transfer the antibodies present in colostrum to the

systemic circuit of newborns (transcytosis), conferring passive immunity. This is dependent on

the expression of a receptor ( Fc ) on the apical membrane of that binds the IgG in breast milk

(Van de Perre, 2003).

The adaptive component of the GI defenses includes the organized lymphoid tissues (e.g.,

Peyer = s patches, mesenteric lymph nodes) that are associated with the GIT and include the B

and T classes of lymphocytes and the antigen presenting dendritic cells (Rumbo and Schiffrin,

2005). A key difference between the adaptive components of the GI and systemic immune

systems, despite sharing similar cell types, is the development of oral tolerance whereby the GI

immune system > learns = to discriminate between bacteria and antigens that pose little or no risk

and those that are dangerous (Magalhaes et al 2007). The learning process has occurred duringthe co-evolution of hosts with their GI bacteria, resulting in receptors and associated signaling

pathways and innate defense mechanisms that can discriminate between the good, the bad, and

the ugly. At birth the cellular and tissue elements of the adaptive component are less abundant



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and immature compared with the adult, with maturation and learning occurring after birth

(Mshvidadze and Neu 2010; Rumbo and Schiffrin, 2005). The even more immature status of the

GI defenses of preterm infants with increased and less regulated NF- B signaling contributes to

the hyperresponsiveness of the GIT, the increased risk of GI inflammatory disorders, such as

NEC, and the increased incidence of sepsis (Claud 2009).

Osmoregulation. The osmoregulatory challenges facing the GI tract differ markedly

between fetuses dependent on placental exchange of water and electrolytes and neonates

dependent on processing of milk to obtain electrolytes and water. Chloride channels exist in the

fetal GI epithelium (Murray et al., 1996), but colonic expression of the sodium channel ENaCand absorption of sodium are underdeveloped or are suppressed in fetuses (Watanabe et al.,

1998). This may contribute to the osmoregulatory problems, including sodium imbalances, and

the special nutritional needs of premature infants. Postnatally, the osmoregulatory functions of

the GIT respond to inflammatory cytokines by a combination of decreased ion absorption and

increased chloride secretion. The resulting diarrhea and the loss of electrolytes and water are the

major cause of morbidity and mortality among newborn animals and infants.

Endocrine secretion. Collectively, the regions of the GI tract and the associated organs

(e.g., pancreas) represent the largest endocrine system in the vertebrate body. Furthermore, a

linkage exists between the GI endocrine and immune function, leading to the concept of the GI

immuno-endocrine axis. Specifically, enteroendocrine cells express TLR = s and respond to

lumenal antigens by the production of cytokines and defensins (Selleri et al., 2008; Palazzo et al.,

2007), as well as respond to cytokines and other regulatory molecules originating from GI

immune cells. Hence, GI immune responses to colonizing bacteria can alter endocrine secretions

by the neonatal GI tract, thereby having GI and systemic implications.



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The vast diversity of secreted peptides is critical for regulating GI (e.g., gastrin, secretin,

cholecystokin) and systemic functions (e.g., insulin, glucagon, ghrelin). Despite reports of

prenatal development of GI endocrine cells (Alumets et al., 1983) and expression of receptors

for epidermal growth factor (Chailler and Mnard, 1999), glucagon-like peptide 2 (Burrin et al.,

2003), and cholecystokinin (Bourassa et al., 1999), there is only a fragmentary understanding of

ontogenetic development of the GI endocrine functions.

Detoxification. The GIT plays a role in the detoxification and elimination of ingested

toxins, including drugs and metabolic wastes from the host and the resident bacteria

(Buddington, 2009). This is accomplished by a combination of enzymes that convert anddetoxify noxious molecules and export transporters that eliminate the resulting xenobiotic

compounds. Although xenobiotic converting enzymes are expressed in the liver during late

gestation, ontogenetic patterns of development for the numerous enzymes and transporters

responsible for the detoxification functions of the GIT are not well characterized (Myllynen et

al., 2009).

THE ASSEMBLAGES OF BACTERIA IN THE GIT

The adult GIT is estimated to harbor 400 to 500 species of bacteria, with some estimates

of >800 species and > 7,000 strains (OKeefe, 2008). The majority of the GI bacteria have yet to

be cultured, and although molecular based approaches of detection have increased our

understanding of the bacterial diversity, these methods have provided few insights into the

functional characteristics of the bacteria and their influences on host health (Flint et al 2007).

The GI microbiota also includes fungi, protozoa, yeasts, viruses and bacteriophages (Mackie et

al., 1999) that influence host health and nutrition. Of critical interest are the interactions that

develop between the microbiome and the GIT of infants (Mshvildadze and Neu, 2010).



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Regional distribution

The GIT can be considered as a small ecosystem (Buddington and Weiher, 1999), with

multiple habitats (regions). Within each region there are dynamic interactions among the

resident bacteria, dietary inputs, and the structure and functions of the region that determine the

physical, chemical, and biotic characteristics (Kelly et al., 2005). The interactions are even more

pronounced during the postnatal period when the combination of dietary inputs, the developing

GI functions, and inter-bacterial interactions play central roles in determining the densities,

diversities, and distributions of species that become established within the different regions of

the GIT ecosystem.The acidic stomach of adult monogastric mammals harbors a lower density (


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activities. The proportion of saccharolytic bacteria and SCFA production are higher in the

proximal colon, whereas proteolytic bacteria and the production of putrefactive metabolites are

more prevalent in the distal colon (Macfarlane and Macfarlane, 2003). This distribution

corresponds with the greater distal production of ammonia, phenols, indoles, amines, and other

toxic and carcinogenic metabolites, which in adults contributes to a higher incidence of

colorectal cancer in the distal colon.

Vertical gradients that extend from the epithelium into the lumen also exist for the

distribution of species in the GIT (Kleesen and Blaut, 2005). The populations of bacteria

adherent to or immediately adjacent to the epithelium have a profound impact on the GIT and thehost, yet they are less understood.

Colonization of the neonatal GIT

The sterile GIT of fetuses is rapidly colonized and within 12 h after delivery bacteria can

be detected throughout the entire GIT and at densities (i.e., cfu/g) that are comparable to those of

adults (Mackie et al., 1999). The similar fecal densities of bacteria enumerated in the colons of

infants and adults may reflect a maximum density of bacteria that can be supported by the GIT

(i.e., carrying capacity).

Colonization is a stochastic process and results in individual variation in GI bacterial

assemblages. This is true even among littermates (Tannock et al., 1990), monozygotic twins

(Stewart et al 2005), and even among identical twins (Dicksved et al., 2008). Infants delivered

vaginally are colonized by bacteria originating from the maternal GIT, vagina, skin, and the

surrounding environment (Huurre et al., 2008; Mackie et al 1999). Infants delivered by

caesarian section are not immediately exposed to maternal fecal and vaginal bacteria. Instead,

the initial colonizers are nosocomial, originating from medical staff and the hospital



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environments. Additional bacteria are eventually acquired from the mother (skin, mammary

glands) and from outside the hospital environment. Corresponding with the different sources and

timing of colonization, the assemblages of GI bacteria differ between infants born vaginally and

by caesarian section. The influence of delivery mode on the assemblages is still apparent up to 7

years after birth (Salminen et al., 2004). Other non-diet factors considered to influence the GI

assemblages that colonize and become established are gestational age at delivery, diet, antibiotic

use, and the external environment (Penders et al., 2006). Infants with assemblages considered to

be beneficial with fewer pathogens are typically delivered vaginally, outside of hospitals, and are

exclusively fed breast milk.Which bacteria persist in the GIT is less random, providing supporting evidence for

species specific host-bacteria relations. Notable are the different species of Helicobacter that

have been isolated from different vertebrates (Schrenzel et al., 2010). Hence, not all species of

bacteria entering the GIT, including probiotic species, are able to persist

Ecological principles and the GI bacteria

After the initial period of colonization, inter-bacterial interactions contribute to the

changes in species composition and metabolic activities of the resident bacteria (Flint et al.,

2007; Mackie et al., 1999). This includes the competitive exclusion of pathogens, probiotics,

and other bacteria by commensal bacteria. The mechanisms of exclusion include competition for

nutrients and binding sites and the production of metabolites that are toxic to other groups. The

process of facilitation, which can be described as cooperative relationships among organisms,

leads to further changes in the GI environment resulting in assemblages with different dominant

species. In the GIT, the aerotolerant species that initially dominate reduce oxygen tension and

thereby favor the emergence of anaerobic groups. Another example of inter-bacterial



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interactions is A metabolic cross-feeding @ whereby one group of bacteria produces metabolites

that are used by other groups (Flint et al., 2007). This includes the conversion of lactate

produced by bifidobacteria into butyrate and other SCFA by other anaerobic members of the GI

bacteria. Recent studies have described quorum sensing among the GI bacteria, triggering

adaptive changes in the characteristics of individual bacterial species (Allan and Torres, 2008),

and perhaps host cells (Sperandio et al., 2003). The gradual changes in the species composition

and distributions of the resident bacteria that occur with increasing age are representative of the

ecological principle of succession. Eventually the changes culminate in a A climax community @

of species.

The composition and productivity of the resident species are also influenced by the

stability and extremes of the local environment (Buddington and Weiher, 1999). Environments

that are harsh (e.g., stomach) or subject to frequent and large disturbances (e.g., proximal small

intestine) have lower densities and diversities of species. Ecosystems with the highest densities

and diversities of species are characterized by benign conditions and with intermittent

disturbances of intermediate magnitude that are sufficient to prevent one or a few species from

becoming dominant. In the GIT, the proximal colon provides such an environment and

correspondingly has the greatest densities, diversities, and species evenness of bacteria.

Among infants the greatest disturbances to the GI ecosystem are caused by diarrhea and

the administration of antibiotics. Both cause dramatic declines in the densities and diversities of

the resident, with a shift in the dominant species (Tanaka et al., 2009). This has the potential toinfluence GI development (Mshvildadze and Neu, 2010) and actually increase the risk of NEC

(Cotten et al., 2009). Importantly, the disturbances caused by even short term antibiotic

administration may persist for at least 2 years (Jernberg et al., 2010).



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DIETARY INPUTS DURING POSTNATAL DEVELOPMENT

There is growing appreciation of the influences of diet on the ontogeny of the GIT and

the assemblages of bacteria that colonize and become established (Newburg and Walker, 2006).

Neonatal mammals are dependent on breast milk to varying degrees, ranging from the extreme

dependency of altricial species, such as marsupials and many laboratory rodents, to the very

short periods of suckling for precocial species, such as guinea pigs that begin to eat the adult diet

shortly after birth. Milk composition varies widely among species (Jenness and Sloan, 1970).

Notable is the absence of lactose in the milk of pinnepeds, the high concentration of

oligosaccharides in human milk (Newburg, 2009), and the wide species variation in protein,carbohydrate, and fat content. Milk composition is also not consistent during lactation. The first

milk produced after birth, colostrum, has higher protein content due to the increased levels of

immunoglobulins and a diversity of regulatory proteins. Within days after birth composition

begins to shift from colostrum to mature milk, with the composition typical of the species.

Apparently, milk composition has been refined over evolutionary time to match the unique

species, age, and individual demands of infants.

Manufacturers of formulas for human infants and milk replacers for companion and

production animals attempt to mimic the composition of the target species milk. Present

formulas are relatively simple, with far fewer components than breast milk. There are intense

efforts to identify ingredients that can be added to formulas and milk replacers and will promote

patterns of GI development and establishment of commensal assemblages of bacteria that are

similar to those when infants are fed breast milk and sucklings of other species are allowed to

nurse the dam.

For most species and individuals weaning is a gradual process with a progressive decline



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in milk consumption and an increased dependency on the adult diet to provide energy and

nutrients. During this period, GI functions and the resident assemblages of bacteria gradually

become adult-like. When weaning is sudden or early, diarrhea often results and is accompanied

by changes in the species composition and metabolic activities of the GI bacteria (Lalls et al.,

2007).

Influences of diet on GI development

The rapid postnatal growth and maturation of the GIT are dependent on dietary inputs

and are delayed when neonates are provided TPN rather than fed enterally. The importance of

lumenal nutrients for development of the neonatal GIT has led to the concept of minimal enteral

nutrition ( A trophic feeding @) whereby small amounts of oral nutrients are provided during TPN

to encourage GI growth and maturation and reduce the risk of bacterial translocation and sepsis

(Bombell et al., 2009).

The composition of the food fed to neonates is a determinant of GI growth, maturation,

and health. Colostrum includes immunoglobulins that provide passive immunity to the neonate

and numerous hormones, cytokines, and other regulatory molecules that stimulate GI growth and

maturation, including immune functions (Hanson, 2007). Even just coating the mouth of preterm

neonates with colostrum may be adequate to stimulate development of GI and systemic immune

functions (Rodriquez et al., 2010).

The change in diet composition at weaning triggers changes in enterocyte cytokinetics

and patterns of gene expression, coinciding with changes in absorptive and secretory functions

(Drozdowski et al., 2010). The secretory characteristics of GI accessory organs, including the

pancreas, are also responsive to the diet change at weaning.



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Influence of diet on the developing assemblages of bacteria

The inputs into ecosystems are key determinants of the abundances, diversity, and

production of the resident organisms. Similarly, the assemblages of GI bacteria are responsive to

dietary and host inputs (Koenig et al., 2010; Buddington and Weiher, 1999). This is evident

from the disturbance to the assemblages of GI bacteria induced by prolonged administration of

TPN (Alverdy et al 2005), causing increases in pathogens and risks of secondary diseases

(Harvey et al 2006). It is not surprising that the amount and composition of the diet fed to infants

influence the postnatal changes in the GI bacteria. By doing so, diet indirectly influences

postnatal GIT development and disease resistance (Amarri et al 2006).

A central question surrounding neonatal health and nutrition is A how does breast milk

adventitiously influence the developing assemblage of bacteria? @ The majority of studies report

infants fed breast milk have a lower incidence of disease. This corresponds with higher fecal

densities of lactic acid producing bacteria (e.g., bifidobacteria and lactobacilli) compared with

infants receiving formula (Penders et al., 2006). Breast milk also reduces the densities of

bacteria adherent to the mucosa and this may contribute to the reduced risk of NEC (Van Haver

et al., 2009). Interestingly, providing infants with only a small volume of formula can elicit

dramatic changes in the GI bacteria (Mackie et al., 1999). The different patterns of microbial

gene expression among piglets fed by the sow or given milk replacer (Poroyko et al., 2010)

raises an intriguing possibility that milk has evolved attributes that favor the establishment and

dominance of commensal bacteria that provide health and nutritional benefits and removeundesired species. The discovery of immune modulation and health benefits of nucleotides (Yu,

2002), which include beneficially modulating the GI bacteria (Singhal et al., 2008), led to the

inclusion of nucleotides in infant formulas. Other components of milk reported to provide more



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than energy and nutrients to infants and can modify the resident bacteria include IgA, human

milk oligosaccharides ( HMO ), lactose, lysozyme, and lactoferrin (Newburg, 2009).

A portion of the lactose in milk is not hydrolyzed during transit of the small intestine and

is metabolized by colonic bacteria, causing an increase in breath hydrogen. This is particularly

true among preterm infants (Kien et al., 1998), and exemplifies how diet influences bacterial

metabolism (Gonzlez et al., 2008). Although lactose fermentation has been interpreted as

lactase insufficiency, it may contribute to shifting the lumenal environment to be more conducive

to commensals.

The multi-functional and diverse HMO are the third most abundant component of humanmilk , with species and individual differences in the amounts, types, and proportions (Newburg,

2009). The majority of HMO are not digested during transit of the GIT and are considered to

encourage the establishment of commensal, health promoting bacteria by a combination of

prebiotic properties, serving as receptor mimics for pathogens, and by modulating mucosal

immune functions (Newburg, 2009; Eiwegger et al., 2010). The protein lactoferrin, though

abundant in human, but not cow milk, (Coppa et al., 2006), is absent in present infant formulas.

Lactoferrin is considered to be immunomodulatory (Suzuki et al., 2005), has the potential to

influence the assemblages of bacteria by being bifidogenic (Coppa et al., 2006), and may reduce

sepsis among preterm infants (Venkatesh and Abrams, 2010). Collectively, the components of

milk highlight a co-evolution between milk composition, the developing GIT, and the resident

bacteria. Combined, they effectively enhance the ability of the neonate to cultivate a garden of

health-promoting bacteria. There is also interest in novel ingredients that are not milk based, but

may beneficially influence the species composition of the GI bacteria when fed to infants [e.g.,

prebiotics and probiotics (Sherman et al., 2009)].



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The historical emphasis has been on formula ingredients that improve the species

composition of the GI microbiota. Less considered, but of critical importance, is the influence of

diet on bacterial enzymes (Grnlund et al., 1999), hence metabolism. Bacterial metabolism and

the production of short chain fatty acids ( SCFA ) and other metabolites is related to the types and

amounts of substrates (Macfarlane and Macfarlane, 2003), such as the responses of the GI

bacteria to lactose (Makivvokko et al., 2006). Although total concentrations of fecal SCFA are

similar for preterm infants fed expressed breast milk or a commercial infant formula(P>0.9),

those fed breast milk have higher concentrations of propionate, but relatively less acetate

(Ps


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involve genetic adaptations of the bacteria to the host GIT (Schell et al., 2002). The cooperative

responses of the GI immune system to the different bacteria have established mutualisms (Slack

et al., 2009).

The interactions that occur during an individuals life influence the characteristics of the

host and the assemblages of bacteria (densities, diversity, evenness, regional distribution, and

functional attributes). These interactions are particularly relevant to neonates and have been the

subject of numerous studies and reviews. Specifically, the early responses of the GIT and the

resident bacteria can have lifelong health consequences through epigenetic mechanisms. These

include the ability of some bacteria to alter the patterns of host gene expression, such as patternsof glycosylation for extracellular proteins (Freitas et al., 2002) in ways that benefit both the

commensal bacteria and the host (Bry et al 1996). Another relevant example is the relationship

between early antigen exposure and risk of allergy and asthma later in life; the hygiene

hypothesis (Schreiner et al., 2008).

Less understood are the rapid and reversible interactions during infancy between the GIT

and the bacteria. These transient interactions occur over periods of minutes to hours and allow

the GIT and the resident bacteria to adapt to changing conditions, such as those that occur during

and between meals of varying size and composition.

The interactions between the bacteria and the GIT can be direct, via cell-to-cell contacts.

Typically, the adverse influences of pathogenic bacteria require direct contact with epithelial

cells and are mediated by surface molecules (Zoumpopoulou et al., 2009). Exemplary is how

attachment of pathogenic E. coli, Salmonella, Clostridia , and other pathogens is required to

trigger the expression of virulence genes, such as those coding for toxins, invasive mechanisms,

or Type III secretion systems that alter the characteristics or cause the death of the attached



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enterocytes. Members of the commensal bacteria and some probiotic strains are considered to

inhibit pathogen adherence and pathogenesis by occupying sites of attachment and by inducing

enterocyte expression of the mucin encoding gene MUC2 and other defense genes that inhibit

attachment (Kim et al., 2008) by the production of immunomodulatory molecules (Mazmanian et

al., 2005).

The influences of the bacteria can also be indirect and mediated by metabolites that alter

host gene expression, beneficially or adversely. Some species of Bifidobacteria release soluble

factors that decrease epithelial cell secretion of inflammatory cytokines (Heuvelin et al., 2009)

and chloride (Heuvelin et al., 2010). SCFA produced by bacterial fermentation of undigestedfeedstuffs provide up to 10% of the total metabolic energy requirement of humans and even

higher percentages among animals with larger hindguts or rumens (Rechkemmer et al 1988).

Corresponding with this, gnotobiotic rodents require 30% more dietary energy and vitamin

supplements compared with conventional rodents harboring commensal bacteria capable of

fermenting undigested feedstuffs. SCFA influence colon health (Wong et al., 2006), alter

patterns of epithelial cell gene expression (Sanderson, 2004; Vanhoutuin et al., 2009), and

stimulate secretion of regulatory peptides that enhance growth and functions of the proximal

small intestine (Bartholme et al., 2004). The responses to butyrate are more pronounced than to

acetate and propionate (Basson et al., 2000). However, excessive production of SCFA, including

butyrate, has been associated with damage to the GI epithelium and may contribute to NEC (Lin

et al., 2005).

Often overlooked is the competition between the GIT and the resident bacteria for

nutrients. Maintaining lower densities of bacteria in the proximal small intestine by peristalsis

and antibacterial secretions from the pancreas and intestine provides the GIT with the first access



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to readily available, digestible nutrients. Food not available to the host can and will be

metabolized by the bacteria.

The resident bacteria influence the developing GIT

There are profound differences between germ-free and conventional rodents with respect

to villus architecture, and enterocyte patterns of proliferation, differentiation, and gene

expression (Zocco et al., 2007) and mucosal immune responses (Williams et al., 2006; Hrncir et

al., 2008). Bacteria isolated from the GITs of neonates are reported to enhance maturation of the

GIT by modulating gene expression (Are et al., 2008). This includes the age-related shifts in the

activities of the fucosyl- and sialyltransferases responsible for the weaning related changes in the

glycosylation of enterocyte glycoproteins (Nanthakamur et al., 2005). Even patterns of intestinal

motility are responsive to the resident bacteria (Lesniewska et al 2006).

The interactions between the colonizing bacteria and the developing GI immune

functions have immediate and long-term consequences on host health (Dimmitt et al., 2010;

Mshvildadze and Neu, 2010). The combination of colonizing bacteria, food, and environmental

antigens activate the immature GI immune system of the neonate by triggering the rapid

maturation, proliferation, and migration of the cellular components of the adaptive immune

division. The interactions during infancy are critical for development of tolerance and the risk of

allergies to food and other environmental antigens later in life (Kukkonen et al. 2008) and are a

key factor in the risk of atopic disorders (Penders et al., 2007). The interactions between the

bacteria and GI epithelial cells also influence innate immune functions, such as the secretion of

mucous and antimicrobial peptides. Additional immunologic challenges at weaning caused by

the concurrent shifts in diet and the GI bacteria trigger further changes in GI defense functions.

Different species of colonizing bacteria have varying influences on the expression of pro-



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inflammatory genes (Zeuthen et al., 2010), the balance between Th1 (antibody mediated) and

Th2 (cell mediated) immune responses (Ogra, 2010), including immunoglobulin production

(Huurre et al., 2008), the patterns of expression for the TLR and NOD that are critical for antigen

discrimination (Lundin et al 2008), and development of tolerance to endotoxins (Lotz et al.,

2006). These findings have stimulated interest in providing probiotics to infants to

adventitiously modulate the developing immune responses. Conversely, changes in the GI

bacteria caused by administration of antibiotics during suckling increases the densities and

responses of mast cells, apparently predisposing to development of allergies (Nutten et al., 2007)

and potentially altering GI immune development (Schumann et al., 2005).There is much less known about if and how the assemblages of bacteria influence the

postnatal development of other GI functions. Despite the impact of pathogen-induced diarrheas

on neonates, the short and long-term responses of the osmoregulatory functions to the colonizing

bacteria have not been described. There is evidence that enteroendocrine cells can directly

respond to resident bacteria by the secretion of hormones (Palazzo et al 2007). The hyperactive

immune responses of the neonate, if stimulated, can be expected to influence the other GI

functions. For example, inflammatory cytokines secreted in response to pathogenic bacteria are

likely to reduce digestive secretions and nutrient absorption and increase the secretion of

electrolytes and water.

The developing GIT influences the resident bacteria

The GIT functions are key determinants of the chemical characteristics of the lumenal

environment. Digestive secretions present barriers to the introduction of species, even probiotics

as well as pathogens. Therefore, the changes in the physicochemcial environment of the

developing GIT (Sanderson, 1999) and the developing innate and adaptive components of the GI



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immune system have the potential to influence the developing assemblages of bacteria

(Salzmann et al., 2010). The immature gastric acid production of neonates (Grahnquist et al.,

2000) coincides with higher densities of bacteria in the stomach until acid production increases.

Postnatal changes in patterns of enterocyte glycosylation of apical membrane glycoproteins

(Nanthakumar et al., 2005) influence bacterial metabolism and may represent a co-evolved

symbiosis between the host and the commensal GI bacteria.

NECROTIZING ENTEROCOLITIS: WHEN THE INTERACTIONS GO AWRY

The interactions among the resident bacteria, the developing GIT, and diet are of key

importance for the adaptation of neonates to postnatal life (Mshvildadze and Neu, 2010). They

are even more important following preterm birth because of the immature state of GI

development, the intolerance of many preterm infants to feeding, and the adverse reactions they

have to colonizing bacteria. Necrotizing enterocolitis is an inflammatory reaction that is the

most common GIT disorder of neonates, and particularly those born premature, with the

incidence varying from 1 to 8% among neonatal intensive care units (Koloske, 2008). The NEC

disease process is multifactorial, with prematurity, bacterial colonization of the GIT, and feeding

recognized as the key contributors. Necrotizing enterocolitis has also been associated with

altered GI bacterial assemblages (Hllstrm et al., 2004), an immature epithelial barrier and

immune defenses, and fetal enterocytes that are hyper-responsive (Claud, 2009). This has led to

the routine prophylactic administration of antibiotics to preterm, low birth weight infants.

Unfortunately, this may actually predispose preterm infants to NEC (Cotten et al, 2009) by

destabilizing the assemblages of GI bacteria. Additionally, the majority of preterm infants are

delivered by caesarian section, which may compromise the normal postnatal spontaneous

activation of intestinal epithelial cells (Lotz et al., 2006) and the already impaired recognition of



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lipopolysaccharide ( LPS ) characteristic of preterm birth (Wolfs et al., 2010). Another issue

facing preterm infants is the initial dependence many have on parenteral nutrition, which delays

GI growth and maturation (Hay, 2008). As a consequence, development of the GI ecosystem is

often compromised among preterm infants (Mshvildadze et al., 2008).

The absence of NEC among germ-free animals demonstrates the essential role of the

resident bacteria in the disease process. Moreover, the risk of NEC is elevated when formula is

fed, whereas infants fed breast milk are protected. This has been corroborated in studies with

animal models (newborn mice and rats) that indicate diet is a determinant of NEC risk via effects

both on microbiota composition and the hosts response pathways (Sodhi et al., 2008). Becausenewborn laboratory rodents have limited physiological, anatomical and developmental relevance

to preterm humans, we recently developed a preterm pig model of NEC to better understand the

diet-microbiota interactions during early GI development in humans (Sangild et al., 2006). Our

studies confirmed that caesarean section and vaginal birth of preterm pigs (at 92% of gestation)

resulted in widely different patterns of GI bacterial colonization, yet resulted in similar

incidences of NEC (Siggers et al., 2010). When preterm, caesarean-delivered pigs are reared in

infant incubators and fed an infant formula, 50% or more spontaneously develop NEC symptoms

and the characteristic lesions. The incidence of NEC is about 5% when preterm pigs are instead

fed sow or cow colostrum (Bjrnvad et al., 2008). This parallels the benefits of providing

colostrum to preterm human infants.

The protection provided by colostrum versus the increased risk associated with formula

indicates dietary inputs play a central role in NEC. If and how diet influences bacterial

colonization of the GIT and the role in NEC has been investigated in the pig model in several

studies (reviewed by Siggers et al., 2010). Overall, there were few diet-dependent differences in



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gut colonization, except that certain pathogenic species (e.g. Clostridium perfringens ) were

consistently associated with intestinal lesions associated with NEC. Moreover, the patterns of

bacterial colonization correlated more closely with the degree of intestinal lesions and gestational

age at birth (maturity of the epithelium) than with specific diets (colostrum vs. formula).

Reviews of clinical trials with human preterm infants that evaluated the efficacy of

probiotics as a prophylactic for NEC suggests NEC risk is reduced (Alfaleh et al,, 2010).

However, the use of different strains of probiotics and administration regimes confounds

interpretations. The administration of probiotics to preterm pigs did not induce notable changes

in the GI bacteria, nor did it consistently reduce the incidence of NEC (Siggers et al., 2010).Although the potential benefits of including prebiotics in formula fed to preterm infants have not

been adequately investigated and remain uncertain (Sherman et al., 2009), studies with animal

models suggest adding prebiotics may reduce the risk of NEC (Butel et al 2002). However, the

addition of prebiotic compounds to the formula fed to preterm pigs failed to improve NEC

resistance relative to the formula alone (Mller et al., 2010). Collectively, these studies lead to

the conclusion that the presence of bacteria is essential for intestinal inflammatory reactions in

newborns. Furthermore, the state of the mucosa is an important determinant of whether the

contact with the colonizing bacteria results in severe inflammation and NEC. Controlling the

process of bacterial colonization in preterm newborns using diet is difficult. Even so, the species

composition of the GI bacteria appears to be less important for NEC risk than the digestive

capacity and immune responses of the immature GIT.

The detrimental effects of feeding formula may be related to the absence of

immunomodulatory factors and nutrients that are present in breast milk and the responses of the

preterm GI ecosystem to novel, non-milk ingredients that are present in formula (e.g., corn syrup



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solids). Preterm pigs fed formula prepared with corn syrup solids have a higher incidence of

NEC compared with when lactose is the dominant source of carbohydrate (Buddington et al.,

2008). The beneficial effects of the lactose-based formula were more closely related to

improved functions of the intestinal mucosa rather than to an improved gut microbiota (Thymann

et al., 2009).

Even though bacteria colonize the GIT immediately after delivery and are present during

the period of TPN, the onset of NEC-related inflammatory reactions in the majority of preterm

pigs occurs within hours after the onset of enteral feeding with formula (Oste et al., 2010). The

importance of diet is again evident from the overfed, preterm rat pup as a model for NEC (Okadaet al., 2010). The importance of diet for inducing NEC in animal models is similar to the

development of NEC in preterm human infants after the start of enteral feeding. These findings

highlight how adverse interactions between the colonizing bacteria and diet in conjunction with

immaturity of the GIT are central to the NEC disease process. Despite the role of GI

microbiome in contributing to disease in infants, it is very likely the metabolic functions of the

GI bacteria and the responses to enteral nutrients are more important in triggering NEC. Rectal

introduction of SCFA induces mucosal damage (Lin et al., 2002) and introducing a combination

of lactose and lactose-fermenting bacteria that generate high concentrations of SCFA (Waligora-

Dupriet et al., 2009) induces mucosal damage and NEC-like characteristics in animal models.

Although the etiology of NEC remains uncertain, the interactions between the GI bacteria and

diet are key determinants of the sensitivity of the immature GIT to stimuli that elicit detrimental

inflammatory reactions.



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PERSPECTIVES FOR DIETARY MANAGEMENT OF THE DEVELOPING GIT

ECOSYSTEM

The type (breast milk or formulas with novel ingredients) and amount (full, minimal, or

absence) of enteral diet in conjunction with bacterial colonization play significant roles in

mediating postnatal development of GI structure, functions, and the resident microbiota. Present

infant formulas fail to replicate the important protective effects of breast milk, which can be

attributed to the lack of bioactive constituents that modulate GI gene expression, growth and

maturation of GI functions, possess antimicrobial functions and provide the neonate with passive

immunity, and others with prebiotic properties that contribute to the selection and dominance of the commensal microbiota.

In addition to providing adequate energy and nutrients, the optimal diet for the neonate,

term or preterm, needs to include components that reduce or prevent the harmful actions of the

resident GI microbiota on the neonatal mucosa. There is understandable interest in increasing

the proportion of beneficial bacteria in the GIT of infants to modulate enteric immune functions

and thereby improve resistance to GIT pathogens and other health challenges (Dogi et al., 2008).

Three principal approaches have been used to date. Although antibiotics remain a mainstay for

neonatal care, there is a growing appreciation and concern of the long-term consequences

associated with the disturbances they cause in the developing GI ecosystem (Cotton et al., 2009;

Jernberg et al., 2010). Probiotics are of widespread interest and there are numerous reports of

efficacy. However, the benefits are generally transient and do not persist after the probiotic is no

longer administered. It has proven possible to provide probiotic bacteria during pregnancy to

facilitate colonization of infants born vaginally (Buddington et al., 2010). However, the

numerous strains available, the varying responses that can be elicited, and likely individual



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specific responses complicate the selection of strains that provide benefits. The emergence of

prebiotics as ingredients in infant formulas mimics the presence of oligosaccharides in breast

milk and has shown promise for encouraging the growth of beneficial bacteria already resident in

and presumably adapted to the host GIT (Veereman, 2007), thereby providing health benefits

(Arslanoglu et al., 2008).

Animal models will remain important for investigating development of the GI ecosystem

human infants, agricultural species, and companion animals and for evaluating the influences of

bacteria and diet. The variation in the GI microbiota among species, individuals, ages, and

health states will complicate extrapolating results from one species to another. It is notsurprising responses to probiotics and prebiotics vary among species and even individuals

(Sullivan and Nord, 2005). A better understanding of how diet influences host-microbiome

interactions during the neonatal period will greatly enhance efforts to improve management of

the GIT ecosystem and thereby the health and nutrition of newborns.

LITERATURE CITED

Alfaleh, K., J. Anabrees, and D. Bassler. 2010. Probiotics reduce the risk of necrotizing

enterocolitis in preterm infants: a meta-analysis. Neonatology 97:93-99.

Allen, C. A., and A. G. Torres. 2008. Host-microbe communication within the GIT. Adv. Exp.

Med. Biol. 635:93-101.

Alumets, J., R. Hkanson, and F. Sundler. 1983. Ontogeny of endocrine cells in porcine gut and

pancreas. An immunocytochemical study. Gastroenterology 85:1359-1372.

Alverdy, J., O. Zaborina, L. W. 2005. The impact of stress and nutrition on bacterial-host

interactions at the intestinal epithelial surface. Curr. Opin. Clin. Nutr. Metab. Care 8:205-



30/46

29

209.

Amarri, S., F. Benatti, M. L. Callegari, Y. Shahkhalili, F. Chauffard, F. Rochat, K. J. Acheson,

C. Hager, J. Benyacoub, E. Galli, A. Rebecchi, and L. Morelli. 2006. Changes of gut

microbiota and immune markers during the complementary feeding period in healthy

breast-fed infants. J. Pediatr. Gastroenterol. Nutr. 42:488-495.

Are, A., L. Aronsson, S. Wang, G. Greicius, Y. K. Lee, J. A. Gustafsson, S. Pettersson, and V.

Arulampalam. 2008. Enterococcus faecalis from newborn babies regulate endogenous

PPARgamma activity and IL-10 levels in colonic epithelial cells. Proc. Natl. Acad. Sci.

USA. 105:1943-1948.Arslanoglu, S., G. E. Moro, J. Schmitt, L. Tandoi, S. Rizzardi, and G. Boehm. 2008. Early

dietary intervention with a mixture of prebiotic oligosaccharides reduces the incidence of

allergic manifestations and infections during the first two years of life. J. Nutr. 138:1091-

1095.

Arslanoglu, S., G. E. Moro, and G. Boehm. 2007. Early supplementation of prebiotic

oligosaccharides protects formula-fed infants against infections during the first 6 months

of life. J. Nutr. 137:2420-2424.

Bailey, M., and K. Haverson. 2006. The postnatal development of the mucosal immune system

and mucosal tolerance in domestic animals. Vet. Res. 37:443-453.

Bartholome, A. L., D. M. Albin, D. H. Baker, J. J. Holst, and K. A. Tappenden. 2004.

Supplementation of total parenteral nutrition with butyrate acutely increases structural

aspects of intestinal adaptation after an 80% jejunoileal resection in neonatal piglets. J.

Parenter. Enteral Nutr. 28:210-222.

Basson, M. D., Y. W. Liu, A. M. Hanly, N. J. Emenaker, S. G. Shenoy, and B. E. Gould



31/46

30

Rothberg. 2000. Identification and comparative analysis of human colonocyte short-chain

fatty acid response genes. J. Gastrointest. Surg. 4:501-512.

Bjornvad, C. R., T. Thymann, N. E. Deutz, D. G. Burrin, S. K. Jensen, B. B. Jensen, L. Molbak,

M. Boye, L. I. Larsson, M. Schmidt, K. F. Michaelsen, and P. T. Sangild. 2008. Enteral

feeding induces diet-dependent mucosal dysfunction, bacterial proliferation, and

necrotizing enterocolitis in preterm pigs on parenteral nutrition. Am. J. Physiol.

Gastrointest. Liver Physiol. 295:G1092-G1103.

Bombell, S., and W. McGuire. 2009. Early trophic feeding for very low birth weight infants.

Cochrane Database Syst. Rev. 8:CD000504.Bourassa, J., J. Lain, M. L. Kruse, M. C. Gagnon, E. Calvo, and J. Morisset. 1999. Ontogeny

and species differences in the pancreatic expression and localization of the CCK(A)

receptors. Biochem. Biophys. Res. Commun. 260:820-828.

Bry, L., P. G. Falk, T. Midtvedt, and J. L. Gordon. 1996. A model of host-microbial interactions

in an open mammalian ecosystem. Science 273:1380-1383.

Buddington, R. K. 2009. Using probiotics and prebiotics to manage the gastrointestinal tract

ecosystem. In: Prebiotics and Probiotics Science and Technology (Charalampopoulos,

D., and R. A. Rastall, eds), Springer Science Publishing, Chapter 1, pp. 1-31.

Buddington, R. K. 1994. Nutrition and ontogenetic development of the intestine. Can. J. Physiol.

Pharmacol. 72:251-259.

Buddington, R.K., S.B Bering, T. Thymann, and P.T. Sangild. 2008 Aldohexose malabsorption

in preterm pigs is directly related to the severity of necrotizing enterocolitis. Pediatr

Res. 63:382-7.

Buddington, R. K., and E. Weiher. 1999. The application of ecological principles and



32/46

31

fermentable fibers to manage the gastrointestinal tract ecosystem. J Nutr. 129

(Suppl):1446S-1450S.

Buddington, R.K., C. H. Williams, B. M. Kostek, K. K. Buddington, and M. J. Kullen. 2010.

Maternal-to-infant transmission of probiotics: concept validation in mice, rats, and pigs.

Neonatology 2010:250-256.

Burrin, D., X. Guan, B. Stoll, Y. M. Petersen, and P. T. Sangild. 2003. Glucagon-like peptide 2:

a key link between nutrition and intestinal adaptation in neonates? J. Nutr. 133:3712-

3716.

Butel, M. J., A. J. Waligora-Dupriet, and O. Szylit. 2002. Oligofructose and experimental modelof neonatal necrotising enterocolitis. Br. J. Nutr. 87 (Suppl):S213-S219.

Chailler, P., and D. Mnard. 1999. Ontogeny of EGF receptors in the human gut. Front. Biosci.

4:D87-D101.

Claud, E. C. 2009. Neonatal necrotizing enterocolitis - inflammation and intestinal immaturity.

Antiinflamm. Antiallergy Agents Med. Chem. 8:248-259.

Conroy, M. E., H. N. Shi, and W. A. Walker. 2009. The long-term health effects of neonatal

microbial flora. Curr. Opin. Allergy Clin. Immunol. 9:197-201.

Coppa, G. V., L. Zampini, T. Galeazzi, and O. Gabrielli. 2006. Prebiotics in human milk: a

review. Dig. Liver Dis. 38 (Suppl):S291-S294.

Cotten, C. M., S. Taylor, B. Stoll, R. N. Goldberg, N. I. Hansen, P. J. Snchez, N. Ambalavanan,

D. K. Benjamin. 2009. NICHD Neonatal Research Network. Prolonged duration of initial

empirical antibiotic treatment is associated with increased rates of necrotizing

enterocolitis and death for extremely low birth weight infants. Pediatrics 123:58-66.

Dimmitt, R. A., E. M. Staley, G. Chuang, S. M. Tanner, T. D. Soltau, and R. G. Lorenz. 2010.



33/46

32

Role of postnatal acquisition of the intestinal microbiome in the early development of

immune function. J. Pediatr. Gastroenterol. Nutr. 51:262-273.

Dicksved, J., J. Halfvarson, M. Rosenquist, G. Jrnerot, C. Tysk, J. Apajalahti, L. Engstrand, and

J. K. Jansson. 2008. Molecular analysis of the gut microbiota of identical twins with

Crohn's disease. ISME J. 2:716-727.

Dogi, C. A., C. M. Galdeano, and G. Perdign. 2008. Gut immune stimulation by non pathogenic

Gram(+) and Gram(-) bacteria. Comparison with a probiotic strain. Cytokine 41:223-231.

Drozdowski, L. A., T. Clandinin, and A. B. Thomson. 2010. Ontogeny, growth and development

of the small intestine: Understanding pediatric gastroenterology. World J. Gastroenterol.16:787-799.

Dunne, C. 2001. Adaptation of bacteria to the intestinal niche: probiotics and gut disorder.

Inflamm. Bowel Dis. 7:136-145.

Eckmann, L. 2006. Innate immunity. In: Physiology of the Gastrointestinal Tract, 4 th Ed

(Johnson, L. R., K. E. Barrett, F. K. Ghishan, J. L. Merchant, H. M. Said, and J. Wood,

eds.), Elsevier, pp. 1033-1066.

Eiwegger, T., B. Stahl, P. Haidl, J. Schmitt, G. Boehm, E. Dehlink, R. Urbanek, and Z.

Szpfalusi. 2010. Prebiotic oligosaccharides: In vitro evidence for gastrointestinal

epithelial transfer and immunomodulatory properties. Pediatr. Allergy. Immunol.

21:1179-1188.

Flint, H. J., S. H. Duncan, K. P. Scott, and P. Louis. 2007. Interactions and competition within

the microbial community of the human colon: links between diet and health. Environ.

Microbiol. 9:1101-1111.

Freitas, M., L. G. Axelsson, C. Cayuela, T. Midtvedt, and G. Trugnan. 2002. Microbial-host



34/46

33

interactions specifically control the glycosylation pattern in intestinal mouse mucosa.

Histochem. Cell Biol. 118:149-161.

Fujiwara, S., Y. Seto, A. Kimura, and H. Hashiba. 2001. Establishment of orally-administered

Lactobacillus gasseri SBT2055SR in the gastrointestinal tract of humans and its influence

on intestinal microflora and metabolism. J. Appl. Microbiol. 90:343-352.

Gonzlez, R., E. S. Klaassens, E. Malinen, W. M. de Vos, and E. E. Vaughan. 2008. Differential

transcriptional response of Bifidobacterium longum to human milk, formula milk, and

galactooligosaccharide. Appl. Environ. Microbiol. 74:4686-4694.

Grahnquist, L., T. Ruuska, and Y. Finkel. 2000. Early development of human gastric H,K-adenosine triphosphatase. J. Pediatr. Gastroenterol. Nutr. 30:533-537.

Grnlund, M. M., S. Salminen, H. Mykknen, P. Kero, and O. P. Lehtonen. 1999. Development

of intestinal bacterial enzymes in infants - relationship to mode of delivery and type of

feeding. APMIS 107:655-660.

Hllstrm, M., E. Eerola, R. Vuento, M. Janas, and O. Tammela. 2004. Effects of mode of

delivery and necrotising enterocolitis on the intestinal microflora in preterm infants. Eur.

J. Clin. Microbiol. Infect. Dis. 23:463-470.

Hanson, L. A. 2007. Feeding and infant development breast-feeding and immune function. Proc.

Nutr. Soc. 66:384-396.

Hay, W. W. 2008. Strategies for feeding the preterm infant. Neonatology 94:245-254.

Heuvelin, E., C. Lebreton, M. Bichara, N. Cerf-Bensussan, and M. Heyman. 2010. A

Bifidobacterium probiotic strain and its soluble factors alleviate chloride secretion by

human intestinal epithelial cells. J. Nutr. 140:7-11.

Heuvelin, E., C. Lebreton, C. Grangette, B. Pot, N. Cerf-Bensussan, and M. 2009. Heyman.



35/46

34

Mechanisms involved in alleviation of intestinal inflammation by bifidobacterium breve

soluble factors. PLoS One 4:e5184.

Hrncir, T., R. Stepankova, H. Kozakova, T. Hudcovic, and H. Tlaskalova-Hogenova. 2008. Gut

microbiota and lipopolysaccharide content of the diet influence development of

regulatory T cells: studies in germ-free mice. BMC Immunol. 9:65.

Huurre, A., M. Kalliomki, S. Rautava, M. Rinne, S. Salminen, and E. Isolauri. 2008. Mode of

delivery - effects on gut microbiota and humoral immunity. Neonatology 93:236-240.

Jenness, R., and R. E. Sloan. 1970. The composition of milks of various species: a review. Dairy

Sci. 32:599-612.Jernberg, C., S. Lfmark, C. Edlund, and J. K. Jansson. 2010. Long-term impacts of antibiotic

exposure on the human intestinal microbiota. Microbiology 156:3216-3223.

Kelly, D., T. King, and R. Aminov. 2007. Importance of microbial colonization of the gut in

early life to the development of immunity. Mutat Res. 622:58-69.

Kien, C. L., R. E. McClead, and L. Cordero Jr. 1998. Effects of lactose intake on lactose

digestion and colonic fermentation in preterm infants. J Pediatr. 133:401-405.

Kim, Y., S. H. Kim, K. Y. Whang, Y. J. Kim, and S. Oh. 2008. Inhibition of Escherichia coli

O157:H7 attachment by interactions between lactic acid bacteria and intestinal epithelial

cells. J. Microbiol. Biotechnol. 18:1278-1285.

Kleessen, B., and M. Blaut. 2005. Modulation of gut mucosal biofilms. Br. J. Nutr.

93(Suppl):S35-S40.

Koenig JE, Spor A, Scalfone N, Fricker AD, Stombaugh J, Knight R, Angenent LT, Ley RE.

2010. Microbes and Health Sackler Colloquium: Succession of microbial consortia in



36/46

35

the developing infant gut microbiome. Proc. Natl. Acad. Sci. U S A. [Epub ahead of

print]

Kosloske, A., Epidemiology of necrotizing enterocolitis. 2008. Acta Paediatrica 83:2-7.

Kukkonen, K., E. Savilahti, T. Haahtela, K. Juntunen-Backman, R. Korpela, T. Poussa, T. Tuure,

and M. Kuitunen. 2008. Long-term safety and impact on infection rates of postnatal

probiotic and prebiotic (synbiotic) treatment: randomized, double-blind, placebo-

controlled trial. Pediatrics 122:8-12.

Lacroix-Lamand, S., N. Rochereau, R. Mancassola, M. Barrier, A. Clauzon, and F. Laurent.

2009. Neonate intestinal immune response to CpG oligodeoxynucleotide stimulation.PLoS One 4:e8291.

Lalls JP, Bosi P, Smidt H, Stokes CR. 2007. Nutritional management of gut health in pigs

around weaning. Proc. Nutr. Soc. 66:260-8.

Lebenthal, A., and E. Lebenthal. 1999. The ontogeny of the small intestinal epithelium. J.

Parenter. Enteral. Nutr. 23(Suppl):S3-S6.

Lesniewska, V., I. Rowland, H. N. Laerke, G. Grant, and P. J. Naughton. 2006. Relationship

between dietary-induced changes in intestinal commensal microflora and duodenojejunal

myoelectric activity monitored by radiotelemetry in the rat in vivo. Exp. Physiol. 91:229-

237.

Ley, R. E., M. Hamady, C. Lozupone, P. J. Turnbaugh, R. R. Ramey, J. S. Bircher, M. L.

Schlegel, T. A. Tucker, M. D. Schrenzel, R. Knight, and J. I. Gordon. 2008. Evolution of

mammals and their gut microbes. Science 320:1647-1651.

Lin, J., L. Peng, S. Itzkowitz, I. R. Holzman, and M. W. Babyatsky. 2005. Short-chain fatty acid

induces intestinal mucosal injury in newborn rats and down-regulates intestinal trefoil



37/46

36

factor gene expression in vivo and in vitro. J. Pediatr. Gastroenterol. Nutr. 41:607-611.

Lotz, M., D. Gtle, S. Walther, S. Mnard, C. Bogdan, and M. W. Hornef. 2006. Postnatal

acquisition of endotoxin tolerance in intestinal epithelial cells. J. Exp. Med. 203:973-984.

Lundin, A., C. M. Bok, L. Aronsson, B. Bjrkholm, J. A. Gustafsson, S. Pott, V. Arulampalam, J

Rafter, and S. Pettersson. 2008. Gut flora, Toll-like receptors and nuclear receptors: a

tripartite communication that tunes innate immunity in large intestine. Cell. Microbiol.

10:1093-1103.

Macfarlane, S., and G. T. Macfarlane. 2003. Regulation of short-chain fatty acid production.

Proc. Nutr. Soc. 62:67-72.Mackie, R. I., A. Sghir, and H. R. Gaskins. 1999. Developmental microbial ecology of the

neonatal gastrointestinal tract. Am. J. Clin. Nutr. 69:1035S-1045S.

Magalhaes, J. G., I. Tattoli, and S. E. Girardin. 2007. The intestinal epithelial barrier: how to

distinguish between the microbial flora and pathogens. Semin. Immunol. 19:106-115.

Mahowald, M. A., F. E. Rey, H. Seedorf, P. J. Turnbaugh, R. S. Fulton, A. Wollam, N. Shah, C.

Wang, V. Magrini, R. K. Wilson, B. L. Cantarel, P. M. Coutinho, B. Henrissat, L. W.

Crock, A. Russell, N. C. Verberkmoes, R. L. Hettich, and J. I. Gordon. 2009.

Characterizing a model human gut microbiota composed of members of its two dominant

bacterial phyla. Proc. Natl. Acad. Sci. USA. 106:5859-5864.

Mkivuokko, H. A., M. T. Saarinen, A. C. Ouwehand, and N. E. Rautonen. 2006. Effects of

lactose on colon microbial community structure and function in a four-stage semi-

continuous culture system. Biosci. Biotechnol. Biochem. 70:2056-2063.

Mazmanian, S. K., C. H. Liu, A.O. Tzianabos, and D. L. Kasper. 2005. An immunomodulatory

molecule of symbiotic bacteria directs maturation of the host immune system. Cell



38/46

37

122:107-118.

Mller, H.K., T. Thymann, L.N. Fink, H. Frokiaer, A.S. Kvistgaard, and P.T. Sangild. 2011

Bovine colostrum is superior to enriched formulas in stimulating intestinal function and

necrotising enterocolitis resistance in preterm pigs. Br. J. Nutr. 20:1-10.

Mshvildadze, M., and J. Neu. 2010. The infant intestinal microbiome: friend or foe? Early Hum.

Dev. 86 (Suppl):67-71.

Mulder, I. E., B. Schmidt, C. R. Stokes, M. Lewis, M. Bailey, R. I. Aminov, J. I. Prosser, B. P.

Gill, J. R. Pluske, C. D. Mayer, C. C. Musk, and D. Kelly. 2009. Environmentally-

acquired bacteria influence microbial diversity and natural innate immune responses atgut surfaces. BMC Biol. 7:79.

Murray, C. B., S. Chu, and P. L. Zeitlin. 1996. Gestational and tissue-specific regulation of C1C-

2 chloride channel expression. Am. J. Physiol. Lung Cell Mol. Physiol. 271:L829-L837.

Myllynen, P., E. Immonen, M. Kummu, and K. Vhkangas. 2009. Developmental expression of

drug metabolizing enzymes and transporter proteins in human placenta and fetal tissues.

Expert Opin. Drug Metab. Toxicol. 5:1483-1499.

Nanthakumar, N. N., D. Dai, D. Meng, N. Chaudry, D. S. Newburg, and W. A. Walker. 2005.

Regulation of intestinal ontogeny: effect of glucocorticoids and luminal microbes on

galactosyltransferase and trehalase induction in mice. Glycobiology 15:221-232.

Nelson, K. E., S. H. Zinder, I. Hance, P. Burr, D. Odongo, D. Wasawo, A. Odenyo, and R.

Bishop. 2003. Phylogenetic analysis of the microbial populations in the wild herbivore

gastrointestinal tract: insights into an unexplored niche. Environ. Microbiol. 5:1212-

1220.

Newburg, D. S. 2009. Neonatal protection by an innate immune system of human milk



39/46

38

consisting of oligosaccharides and glycans. J. Anim. Sci. 87(Suppl):26-34.

Newburg, D. S., and W. A. Walker. 2007. Protection of the neonate by the innate immune

system of developing gut and of human milk. Pediatr Res. 61:2-8.

Nutten, S., A. Schumann, D. Donnicola, A. Mercenier, S. Rami, and C. L. Garcia-Rodenas.

2007. Antibiotic administration early in life impairs specific humoral responses to an oral

antigen and increases intestinal mast cell numbers and mediator concentrations. Clin.

Vaccine Immunol. 14:190-197.

Ogra, P. L. 2010. Ageing and its possible impact on mucosal immune responses. Ageing Res.

Rev. 9:101-106.Okada, K., T. Fujii, Y. Ohtsuka, Y. Yamakawa, H. Izumi, Y. Yamashiro, and T. Shimizu. 2010.

Overfeeding can cause NEC-like enterocolitis in premature rat pups. Neonatology

97:218-224.

O'Keefe, S. J. 2008. Nutrition and colonic health: the critical role of the microbiota. Curr. Opin.

Gastroenterol. 24:51-58.

Oste, M., E. Van Haver, T. Thymann, P. T. Sangild, A. Weyns, and C. J. Van Ginneken. 2010

Formula induces intestinal apoptosis in preterm pigs within a few hours of feeding. J.

Parenter. Enteral. Nutr. 34:271-279.

Palazzo, M., A. Balsari, A. Rossini, S. Selleri, C. Calcaterra, S. Gariboldi, L. Zanobbio, F.

Arnaboldi, Y. F. Shirai, G. Serrao, and C. Rumio. 2007. Activation of enteroendocrine

cells via TLRs induces hormone, chemokine, and defensin secretion. J. Immunol.

178:4296-4303.

Penders, J., E. E. Stobberingh, P. A. van den Brandt, and C. Thijs. 2007. The role of the

intestinal microbiota in the development of atopic disorders. Allergy 62:1223-1236.



40/46

39

Penders, J., C. Thijs, C. Vink, F. F. Stelma, B. Snijders, I. Kummeling, P. A. van den Brandt, and

E. E. Stobberingh. 2006. Factors influencing the composition of the intestinal microbiota

in early infancy. Pediatrics 118:511-521.

Poroyko, V., J. R. White, M. Wang, S. Donovan, J. Alverdy, D. C. Liu, and M. J. Morowitz.

2010. Gut microbial gene expression in mother-fed and formula-fed piglets. PLoS One

5:e12459.

Pritchard, J. A. 1966. Fetal swallowing and amniotic fluid volume. Obstet. Gynecol. 28:606-610.

Quie, P. G. 1990. Antimicrobial defenses in the neonate. Semin Perinatol. 14(Suppl):2-9.

Rechkemmer G, Rnnau K, von Engelhardt W. 1988. Fermentation of polysaccharides andabsorption of short chain fatty acids in the mammalian hindgut. Comp. Biochem. Physiol.

A. 90:563-568.

Richardson, W. M., C. P. Sodhi, A. Russo, R. H. Siggers, A. Afrazi, S. C. Gribar, M. D. Neal, S.

Dai, T. Prindle, M. Branca, C. Ma, J. Ozolek, and D. J. Hackam. 2010. Nucleotide-

binding oligomerization domain-2 inhibits toll-like receptor-4 signaling in the intestinal

epithelium. Gastroenterology 139:904-917.

Rodriguez, N. A., P. P. Meier, M. W. Groer, J. M. Zeller, J. L. Engstrom, L. Fogg. 2010. A pilot

study to determine the safety and feasibility of oropharyngeal administration of own

mother's colostrum to extremely low-birth-weight infants. Adv. Neonatal Care 10:206-

12.

Rumbo, M., and E. J. Schiffrin. 2005. Ontogeny of intestinal epithelium immune functions:

developmental and environmental regulation. Cell. Mol. Life Sci. 62:1288-1296.

Salminen, S., G. R. Gibson, A. L. McCartney, and E. Isolauri. 2004. Influence of mode of

delivery on gut microbiota composition in seven year old children. Gut 53:1388-1389.



41/46

40

Salzman, N. H., K. Hung, D. Haribhai, H. Chu, J. Karlsson-Sjberg, E. Amir, P. Teggatz, M.

Barman, M. Hayward, D. Eastwood, M. Stoel, Y. Zhou, E. Sodergren, G. M. Weinstock

C. L. Bevins, C. B. Williams, and N. A. Bos. 2010. Enteric defensins are essential

regulators of intestinal microbial ecology. Nat. Immunol. 11:76-83.

Sanderson, I. R. 2004. Short chain fatty acid regulation of signaling genes expressed by the

intestinal epithelium. J. Nutr. 134:2450S-2454S.

Sanderson, I. R. 1999. The physicochemical environment of the neonatal intestine. Am. J. Clin.

Nutr. 69:1028S-1034S.

Sanderson IR. 1998. Dietary regulation of genes expressed in the developing intestinalepithelium. Am. J. Clin. Nutr. 68:999-1005.

Sangild, P. T., R. H. Siggers, M. Schmidt, J. Elnif, C. R. Bjornvad, T. Thymann, M. L. Grondahl,

A. K. Hansen, S. K. Jensen, M. Boye, L. Moelbak, R. K. Buddington, B. R. Westrom, J.

J. Holst, and D. G. Burrin. 2006. Diet- and colonization-dependent intestinal dysfunction

predisposes to necrotizing enterocolitis in preterm pigs. Gastroenterology 130:1776-1792.

Schell, M. A., M. Karmirantzou, B. Snel, D. Vilanova, B. Berger, G. Pessi, M. C. Zwahlen, F.

Desiere, P. Bork, M. Delley, R. D. Pridmore, and F. Arigoni. 2002. The genome

sequence of Bifidobacterium longum reflects its adaptation to the human gastrointestinal

tract. Proc. Natl. Acad. Sci. USA 99:14422-14427.

Shreiner, A., G. B. Huffnagle, and M. C. Noverr. 2008. The "Microflora Hypothesis" of allergic

disease. Adv. Exp. Med. Biol. 635:113-134.

Schrenzel, M. D., C. L. Witte, J. Bahl, T. A. Tucker, N. Fabian, H. Greger, C. Hollis, G. Hsia, E.

Siltamaki, and B. A. Rideout. 2010. Genetic characterization and epidemiology of

Helicobacters in non-domestic animals. Helicobacter 15:126-142.



42/46

41

Schumann, A., S. Nutten, D. Donnicola, E. M. Comelli, R. Mansourian, C. Cherbut, I. Corthesy-

Theulaz, and C. Garcia-Rodenas. 2005. Neonatal antibiotic treatment alters

gastrointestinal tract developmental gene expression and intestinal barrier transcriptome.

Physiol Genomics 23:235-245.

Selleri, S., M. Palazzo, S. Deola, E. Wang, A. Balsari, F. M. Marincola, and C. Rumio. 2008.

Induction of pro-inflammatory programs in enteroendocrine cells by the Toll-like

receptor agonists flagellin and bacterial LPS. Int. Immunol. 20:961-970.

Sharma, R., C. Young, and J. Neu. 2010. Molecular modulation of intestinal epithelial barrier:

contribution of microbiota. J. Biomed. Biotechnol. 2010:305879.Sherman, P. M., M. Cabana, G. R. Gibson, B. V. Koletzko, J. Neu, G. Veereman-Wauters, E. E.

Ziegler, and W. A. Walker. 2009. Potential roles and clinical utility of prebiotics in

newborns, infants, and children: proceedings from a global prebiotic summit meeting. J.

Pediatr. 155:S61-S70.

Shibolet, O., and D. K. Podolsky. 2007. TLRs in the Gut. IV. Negative regulation of Toll-like

receptors and intestinal homeostasis: addition by subtraction. Am. J. Physiol.

Gastrointest. Liver. Physiol. 292:G1469-G1473.

Siggers, R. H., J. Siggers, T. Thymann, M. Boye, and P. T. Sangild. 2010. Nutritional

modulation of the gut microbiota and immune system in preterm neonates susceptible to

necrotizing enterocolitis. J. Nutr. Biochem. (In Press).

Singhal, A., G. Macfarlane, S. Macfarlane, J. Lanigan, K. Kennedy, A. Elias-Jones, T.

Stephenson, P. Dudek, and A. Lucas. 2008. Dietary nucleotides and fecal microbiota in

formula-fed infants: a randomized controlled trial. Am. J. Clin. Nutr. 87:1785-1792.

Slack, E., S. Hapfelmeier, B. Stecher, Y. Velykoredko, M. Stoel, M. A. Lawson, M. B. Geuking



43/46

42

B. Beutler, T. F. Tedder, W. D. Hardt, P. Bercik, E. F. Verdu, K. D. McCoy, and A. J.

Macpherson. 2009. Innate and adaptive immunity cooperate flexibly to maintain host-

microbiota mutualism. Science 325:617-620.

Sodhi, C., W. Richardson, S. Gribar, and D. J. Hackam. 2008. The development of animal

models for the study of necrotizing enterocolitis. Dis. Model. Mech. 1:94-98.

Sperandio, V., A. G. Torres, B. Jarvis, J. P. Nataro, and J. B. Kaper. 2003. Bacteria-host

communication: the language of hormones. Proc. Natl. Acad. Sci. USA 100:8951-8956.

Stevens, C. E., and I. D. Hume. 1995.Comparative Physiology of the Vertebrate Digestive

System. 2nd ed. New York: Cambridge University Press.Stewart, J. A., V. S. Chadwick, and A. Murray. 2005. Investigations into the influence of host

genetics on the predominant eubacteria in the faecal microflora of children. J. Med.

Microbiol. 54:1239-1242.

Sullivan, A., and C. E. Nord. 2005. Probiotics and gastrointestinal diseases. J. Intern. Med.

257:78-92.

Suzuki, Y. A., V. Lopez, and B. Lnnerdal. 2005. Mammalian lactoferrin receptors: structure

and function. Cell. Mol. Life Sci. 62:2560-2575.

Tanaka, S., T. Kobayashi, P. Songjinda, A. Tateyama, M. Tsubouchi, C. Kiyohara, T. Shirakawa,

K. Sonomoto, and J. Nakayama. 2009. Influence of antibiotic exposure in the early

postnatal period on the development of intestinal microbiota. FEMS Immunol. Med.

Microbiol. 56:80-87.

Tannock, G. W., R. Fuller, and K. Pedersen. 1990. Lactobacillus succession in the piglet

digestive tract demonstrated by plasmid profiling. Appl. Environ. Microbiol. 6:1310-

1316.



44/46

43

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