BACTERIA

BacteriaAll bacteria share several common

characteristicsUnicellular (although some stick together in

colonies)Prokaryotic – no nucleus, lack most cell

organellesSingle chromosome Reproduce through binary fissionNeed moist environmentHave rigid outer wall that give it shape

Two Kingdoms or Two Domains

Archaebacteriaoccupy environmental

extremesThermoacidophilesHalophilesMethanogensprobable ancestor of

Eukaroyotes

Eubacteriamodern specieshave different

RNA and gene products

includes most of the bacteria encountered in daily life

ArchaebacteriaDesended from one of the oldest groups of

living organisms on earthLive in areas of such extreme conditions

that nothing else survives there

Thermophiles

Live in areas of more than 45 C

Some obtain energy from metabolizing sulfur compounds Live near sulfur hot

springsEnzyme Taq polymerase

(from Thermus aquaticus) is used in molecular genetics (DNA replication)

Grow in areas without oxygen

Use CO2 and H2O to produce methane

Live in volcanic deep-sea vent and mammalian intestines

Used to help digest sewage and oil spills

3 major groupsMethanogens

HalophilesLive in areas that are very saline such as

salt flats and evaporation pondsHave a bright red pigment that allow to

capture sunlight for energyUsed for cancer reasearch

EubacteriaThe most common member of this

Kingdom is Escherichia coliLive in human intestines helping with food

digestion and some vitamin synthesisIn too high levels it can be dangerous

Each new E. coli is about 1m in length (0.00000 1m)A line of 250 could be seen by the naked eye

A distinction of this kingdom is the structure of the cell wall, however not all have a cell wall They have a polymer called peptioglycan

The two types of Eubacteria (with or without a cell wall) can be distinguished by a Gram StrainCells are stained with crystal violet (purple dye)Dye is fixed, cell is “washed” with a decolourizerStained again with safranin (red dye)• Those with peptioglycan retain the purple colour

(Gram Positive) while those without lose the purple and so take on second stain pink (Gram Negative)

• (Staph - +ve , E. Coli –ve)

Streptococcus

Gram Negative

Characterized by 3 shapesA) Cocci spherical ---

B) bacilli rod-shaped ---------------

C) Spirilla spiral

Bacterial Shape

ConfigurationAfter they divide some cells stay together

in groupsIf they form a chain they are given the prefix

strepto Ie. Streptococcus mutans (tooth decay)

If they form a cluster they are given the name staphyloIe. Staphylococcus aureus (found on skin)

Streptobacillus

Bacterial Shape

staphylococcus

streptococcus

diplococcus

streptobacillus

diplobacillus

staphylobacillus

Streptococcus

Streptobacillus

Spirochetes

Helical rods

Tetrads

Typical Bacterial Characteristics

Flagella- whip-like locomotor structure

Pili-hollow tube for attachment or exhange of DNA during conjugation

Cell membrane lies inside wall carries on metabolism and synthesis

Plasmid ring of DNA that may be exchanged between bacteria and may direct antibiotic production

4

•Capsule- for attachment and protection, sticky with various polysaccharides , maycause disease.•Pilis- hollow tubes for attachment or exchange of DNA (conjugation)•Motility- by flagella with some ability to move towards food•Genome- DNA one large circular chromosome and smaller rings of DNA called PLASMIDS•Endospores- resistant stage for survival of harsh conditions

Capsule- for attachment and protection,sticky with various polysaccharides , may cause disease.

Pilis- hollow tubes for attachment or exchange of DNA (conjugation)

NutritionAutotrophs – make their own food from

inorganic substancesPhotosynthetic – convert CO2, H2O and

light energy into carbohydratesChemosynthetic – use chemical reactions to

provide them with energyHeterotrophs – obtain their energy by

consuming other organisms (i.e. Dead, decaying organisms, or by living as parasites on living tissues)

RespirationAnaerobic

does not require itAerobic

Requires O2

ReproductionAsexually through binary fissioni.e. Pyrodictium abyssi

Sexually through Conjugationi.e. Salmonella

Short life cycle 20 min-3 hrs. doubling time

Binnary Fission

Binary Fission

ConjugationGenes are exchanged via a sex pilus

Spore Formation

Endospores- resistant stage for survival of harsh dry or hot environments

Bacterial Pathogens

Endostoxins- protein or other chemical toxins found within the microbe released when cell dies.

Exotoxins- released by pathogen

CAUSE DISEASE

How we Control BacteriaTemperature- exceed range of tolerance

autoclave- heat under pressure pasteurization-heat to below 100 degrees C. refrigiration- slows only, not good for

psychrophilicUV light- destroys DNAChemical antisepic- on living tissue disinfectant-on inanimate objects antibiotic-produced by living things

Koch's postulates (or Henle-Koch postulates) Are four criteria designed to establish a

causal relationship between a causative microbe and a disease.

The postulates were formulated by Robert Koch and Friedrich Loeffler in 1884 and refined and published by Koch in 1890.

Koch applied the postulates to establish the etiology of anthrax and tuberculosis, but they have been generalized to other diseases.

KOCH’S POSTULATEIsolate the suspected pathogen and grow in pure culture

Inoculate a healthy hostLook for symptoms Re-isolate and compare to original pathogen