Chapter 1 History of Microbiology

7/16/2019 Chapter 1 History of Microbiology

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© 2012 Pearson Education Inc.

Lecture prepared by Mindy Miller-Kittrell North Carolina State University

Chapter 1

A Brief

History of

Microbiology



Chapter 1 Assignment

Note: Homework assignments are due at the exam

• Multiple Choice 1-10

• Matching 1-12

• Concept Map

•

List Steps of Scientific Method in order and describeeach one

• Discuss Pasteur’s experiment with the swan necked

flasks investigating spontaneous generation. How

does it exemplify the first 4 steps of the scientific

method. Be specific. What was the experimental

group? Control group? Result?



The Early Years of Microbiology

• What Does Life Really Look Like?

– Antoni van Leeuwenhoek (Dutch)

– Began making and using simple microscopes

– Often made a new microscope for each specimen

– Examined water and visualized tiny animals, fungi,algae, and single-celled protozoa: “animalcules”

– By end of 19th century, these organisms were called

microorganisms




Figure 1.1 Antoni van Leeuwenhoek



Figure 1.2 Reproduction of Leeuwenhoek’s microscope

Specimen holder Lens



Figure 1.3 The microbial world




• How Can Microbes Be Classified? – Carolus Linnaeus developed taxonomic system

for grouping similar organisms together

– Leeuwenhoek’s microorganisms grouped into sixcategories:

– Bacteria

– Archaea

– Fungi – Protozoa

– Algae

– Small multicellular animals





• Bacteria and Archaea

– Unicellular and lack nuclei

– Much smaller than eukaryotes

– Found everywhere there is sufficient moisture – Reproduce asexually

– Two kinds

– Bacteria – cell walls contain peptidoglycan

– Archaea – cell walls composed of polymersother than peptidoglycan




Figure 1.4 Cells of the bacterium Streptococcus

Nucleus of

eukaryotic cheek cellProkaryotic

bacterial cells

Cells of the

bacterium

Streptococ

cus (dark

blue)

and twohuman

cheek

cells.

Notice thesize

difference.




• Fungi

– Eukaryotic (have membrane-bound nucleus)

– Obtain food from other organisms

– Possess cell walls – Include

– Molds – multicellular; grow as long filaments;reproduce by sexual and asexual spores

– Yeasts – unicellular; reproduce by budding or sexual spores




Figure 1.5 Fungi-overview




• Protozoa

– Single-celled eukaryotes

– Similar to animals in nutrient needs and cellular structure

– Live freely in water; some live in animal hosts

– Asexual (most) and sexual reproduction

– Most are capable of locomotion by

– Pseudopodia – Cilia

– Flagella




Figure 1.6 Locomotive structures of protozoa-overview




• Algae

– Unicellular or multicellular

– Photosynthetic

– Simple reproductive structures – Categorized on the basis of pigmentation,

storage products, and composition of cell wall


Fi 1 7 Al i



Figure 1.7 Algae-overview

Fi 1 8 A i t t f iti i bl d



Figure 1.8 An immature stage of a parasitic worm in blood

Red blood cell

Fi 1 9 Vi i f ti b t i



Figure 1.9 Viruses infecting a bacterium

Virus

Bacterium

Viruses

assemblinginside cell



The Golden Age of Microbiology

• Scientists searched for answers to four

questions

– Is spontaneous generation of microbial life

possible? – What causes fermentation?

– What causes disease?

– How can we prevent infection and disease?





• Some thought living things arose from

three processes

– Asexual reproduction

– Sexual reproduction – Nonliving matter

• Aristotle proposed

spontaneous generation(384-322 B.C.)

– Living things can arise from nonliving matter





• Redi’s Experiments

– When decaying meat was kept isolated from

flies, maggots never developed

– Meat exposed to flies was soon infested

– As a result, scientists began to doubt

Aristotle’s theory


Figure 1 10 Redi’s experiments: late 1600s



Figure 1.10 Redi s experiments: late 1600s

Flask unsealed Flask sealed Flask coveredwith gauze




• Needham’s Experiments

– Scientists thought microbes, but not animals,

could arise spontaneously

– Needham’s experiments reinforced this idea





• Spallanzani’s Experiments

– Conclusions

– Needham failed to heat vials sufficiently to kill all

microbes or had not sealed vials tightly enough – Microorganisms exist in air and can contaminate

experiments

– Spontaneous generation does not occur

– Critics argued against experiments – Sealed vials did not allow enough air for

organisms to survive

– Prolonged heating destroyed “life force”


Figure 1 11 Louis Pasteur



Figure 1.11 Louis Pasteur



Th G ld A f Mi bi l




• Pasteur’s Experiments

– When the “swan-necked” flasks remained

upright, no microbial growth appeared

– When the flask was tilted, dust from the bendin the neck seeped back into the flask and

made the infusion cloudy with microbes

within a day


Figure 1.12 Pasteur’s experiments with “swan-necked” flasks



Figure 1.12 Pasteur s experiments with swan necked flasks

Steam escapesfrom open endof flask.

Infusion

is heated.

Infusion sits;

no microbes appear.

Months

Air moves inand out of flask.

Infusion remains

sterile indefinitely.

Dust fromair settlesin bend.

Th G ld A f Mi bi l




• The Scientific Method

*Identify Question

Form Hypothesis

Collect data by performing experiment

*Interpret results If hypothesis is rejected

Peer Review

Publish Findings


Th G ld A f Mi bi l




• The Scientific Method: Pasteur’s experiment

*Identify Question

Form Hypothesis

Collect data by performing experiment

*Interpret results


Figure 1.13 The scientific method



g

Observations

Question

Hypothesis

Repeat

Experiment,includingcontrol groups

Modifiedhypothesis

Observations

Experimentaldata supporthypothesis

Experimentaldata do notsupporthypothesis

Accepthypothesis

Rejecthypothesis

Modifyhypothesis

Theoryor law

Th G ld A f Mi bi l




• What Causes Fermentation?

– Spoiled wine threatened livelihood of vintners

– Some believed air caused fermentation

– Others insisted living organisms causedfermentation

– Vintners funded research to prevent spoilageduring fermentation

– This debate also linked to debate over spontaneous generation


Figure 1.14 Pasteur's application of the scientific method



Observation:

Hypothesis Experiment Observation Conclusion

Fermentinggrape juice

Microscopic analysisshows juice contains

yeasts and bacteria.

Day 1: Flasks of grape

juice are heated sufficiently

to kill all microbes.

Day 2

I. Spontaneous

fermentation

occurs.

II. Air ferments

grape juice.

III. Bacteria ferment

grape juice

into alcohol.

IV. Yeasts ferment

grape juice

into alcohol.

Juice in flask is

inoculated with

yeast and sealed.

Juice in flask is

inoculated with

bacteria and sealed.

Flask remainsopen to air

via curved neck.

Flask issealed.

No fermentation;

juice remainsfree of microbes

No fermentation;

juice remains

free of microbes

Bacteria reproduce;

acids are produced.

Yeasts reproduce;

alcohol is produced.

Reject

hypothesis I.

Reject

hypothesis II.

Modify hypothesis

III; bacteria ferment

grape juice into

acids.

Accept hypothesis

IV; yeasts ferment

grape juice into

alcohol.

Table 1.1 Some Industrial Uses of Microbes







• What Causes Disease?

– Pasteur developed germ theory of disease

– Robert Koch studied causative agents of

disease – Anthrax

– Examined colonies of microorganisms


Figure 1.15 Robert Koch







• Koch’s Contributions

– Simple staining techniques

– First photomicrograph of bacteria

– First photomicrograph of bacteria in diseasedtissue

– Techniques for estimating CFU/ml

– Use of steam to sterilize media

– Use of Petri dishes – Techniques to transfer bacteria

– Bacteria as distinct species


Figure 1.16 Bacterial colonies on agar



Bacterium 1

Bacterium 2

Bacterium 3

Bacterium 4

Bacterium 5

Bacterium 6 Bacterium 7

Bacterium 8

Bacterium 9

Bacterium 10

Bacterium 11

Bacterium 12





• Koch’s Postulates – Suspected causative agent must be found in

every case of the disease and be absent fromhealthy hosts

– Agent must be isolated and grown outsidethe host

– When agent is introduced into a healthy,susceptible host, the host must get the disease

– Same agent must be found in the diseasedexperimental host


Table 1.2 Other Notable Scientists of the “Golden Age of Microbiology” and the Agents of Disease They Discovered







• Gram’s Stain – Danish scientist Hans Christian Gram developed

more important staining technique than Koch’sin 1884

– Involves the applications of a series of dyes

– Some microbes are left purple, now labeledGram-positive

– Other microbes are left pink, now labeled Gram-

negative – Gram procedure used to separate into two

groups


Figure 1.17 Results of Gram staining

G iti G ti



Gram-positive Gram-negative





• How Can We Prevent Infection andDisease?

– Semmelweis and handwashing

– Lister’s antiseptic technique – Nightingale and nursing

– Snow – infection control and epidemiology

– Jenner’s vaccine – field of immunology

– Ehrlich’s “magic bullets” – field of chemotherapy




Semmelweis and Lister video

• http://www.youtube.com/watch?v=T73PYNyyeiI&feature=related

Figure 1.18 Florence Nightingale

http://www.youtube.com/watch?v=T73PYNyyeiI&feature=related






Figure 1.19 Some scientific disciplines and applicationsBIOLOGISTS MODERN DISCIPLINES



BIOLOGISTS MODERN DISCIPLINES

Pre-1857

The Golden Age of Microbiology (1857 –1907)

Leeuwenhoek

Linnaeus

Semmelweiss

Snow

Bacteriology (bacteria)

Protozoology (protozoa)

Mycology (fungi)

Parasitology (protozoa and

animals)

Phycology (algae)

Taxonomy

Infection control

Epidemiology

Pasteur

Pasteurization

Industrial microbiology

Food and beverage technology

Buchner

Koch Koch’s postulates

Ivanowski

Beijerinck

Winogradsky

Gram

Lister

Nightingale

Jenner

von Behring

Kitasato

Ehrlich

Fleming

Microbial metabolism

GeneticsGenetic engineering

Etiology

Virology

Environmental microbiology

Ecological microbiology

Microbial morphology

Antiseptic medical techniques

Hospital microbiology

Serology

Immunology

Chemotherapy

Pharmaceutical microbiology

Table 1.3 Fields of Microbiology



The Modern Age of Microbiology




• What Are the Basic Chemical Reactions of Life?

– Biochemistry

– Began with Pasteur’s and Buchner’s works

– Microbes used as model systems for biochemicalreactions

– Practical applications

– Design of herbicides and pesticides

– Diagnosis of illness and monitoring responses totreatment

– Treatment of metabolic diseases

– Drug design






• How Do Genes Work?

– Microbial genetics

– Molecular biology

– Recombinant DNA technology – Gene therapy






• Microbial Genetics

– Avery, MacLeod, and McCarty: genes are

contained in molecules of DNA

– Beadle and Tatum: a gene’s activity is related toprotein function

– Translation of genetic information into protein

explained

– Rates and mechanisms of genetic mutationinvestigated

– Control of genetic expression by cells described






• Molecular Biology

– Explanation of cell function at the molecular level

– Pauling proposed that gene sequences could

– Provide understanding of evolutionaryrelationships/processes

– Establish taxonomic categories

– Identify microbes that have never been cultured

– Woese determined cells belong to bacteria,archaea, or eukaryotes

– Cat scratch disease caused by unculturable

organism






• Recombinant DNA Technology

– Genes in microbes, plants, and animals

manipulated for practical applications

– Production of human blood-clotting factor byE. coli to aid hemophiliacs

• Gene Therapy

– Inserting a missing gene or repairing a defectiveone in humans by inserting desired gene into

host cells





g gy

• What Roles Do Microorganisms Play in theEnvironment?

– Bioremediation uses living bacteria, fungi,

and algae to detoxify polluted environments

– Recycling of chemicals such as carbon,

nitrogen, and sulfur





g gy

• How Do We Defend Against Disease? – Serology

– The study of blood serum

– Blood contains chemicals and cells that fight

infection

– Immunology

– The study of the body’s defense against specificpathogens

– Chemotherapy – Fleming discovered penicillin

– Domagk discovered sulfa drugs


Figure 1.20 Effects of penicillin on a bacterial “lawn” in a petri dish



Fungus colony(Penici l l ium )

Zone of inhibition

Bacterial colonies(Staphy lococcus )




g gy

• What Will the Future Hold?

– Microbiology is built on asking and answering

questions

– The more questions we answer, the morequestions we have

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Chapter 1 History of Microbiology

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