CHAPTER 11: THE PROKARYOTES

Domains Bacteria and Archaea

The Prokaryotic Groups◦Prokaryotes are divided into two groups◦ Bacteria

◦Archaea

◦See difference on Page 291 figure 10.6

The Proteobacteria

◦ Includes most G(-) bacteria and are thought to

have arisen from a common photosynthetic

organism

◦Largest group of bacteria

Alphaproteobacteria

◦ Typically can grow at a low

level of nutrients

◦Unusual morphology including

buds or stalks

◦ Stalks that are used to adhere to

a surface are called

prosthecae

◦Name comes from the

mythological Greek god

Proteus who could morph into

many shapes

◦Alpha-

◦Beta-

◦Gamma-

◦Delta-

◦Epsilon-

◦Alpha- are very important in

agriculture because many

of these bacteria can fix

nitrogen and can live in

symbiosis with plants and

humans

Azosprillium

◦Rickettsia and Chlamydia

are obligate intracellular

parasites

◦They can only reproduce

within a mammalian cell

◦They are commonly

transmitted within insect

bites and ticks

◦ Spotted fever, typhus, Rocky

Mountain spotted fever

◦Caulobacter bacteria are found

in low-nutrient aquatic

environments

◦ They have prosthecae because

of the constant changing flow of

water

◦Bartonella is a gram (-) bacillus that causes

cat scratch fever

Betaproteobacteria

◦There are many similarities

between alpha- and beta-

◦Often use ammonia,

hydrogen gas, or methane

◦Pathogenic bacteria are

considered

betaproteobacteria

◦Spirillum is found in fresh water and has

polar flagella and is an aerobic organism

◦ Sphaerotilus are sheathed,

G(-) bacteria found in

sewage

◦ The sheath is a protective

layer which provides

protection and a source of

nutrient accumulation

◦Bordetella is the group of bacteria responsible for

whooping cough. It is nonmotile, aerobic, and

G(-)

◦Neisseria are aerobic,

G(-), cocci that live in

mucosal membranes

of mammals

◦Pathogens in this groups

cause gonorrhea and

meningitis.

Gammaproteobacteria

◦Largest

subgroup of

Proteobacteria

◦Pseudomonas is aerobic, G(-) rods with

polar flagella

◦Very common in soil

◦ Infects urinary tract, burns, wounds

◦ Some species have evolved to grow

inside some antiseptics

◦Moraxella is a group of bacteria that cause

conjunctivitis

◦Vibrio bacteria are facultatively

anaerobic, G(-) slightly curved rods

◦Cause of cholera and gastroenteritis

◦Salmonella is potentially

pathogenic

◦They inhabit intestine tracts

of many animals

◦Causes Typhoid fever and

salmonellosis

Deltaproteobacteria

◦ Include bacteria that prey on other bacteria.

They are predators.

◦Desulfovibrio are obligately anaerobic bacteria

that form hydrogen sulfide

◦Can be found in the intestinal tracts of humans

◦Myxococcus leave behind a slime trail and

they get their energy by lysing other

bacteria

Epsilonproteobacteria

◦ Slender G(-) rods that are helical or vibrio and are

microaerophile

◦Heliobacter is the

most common

cause of peptic

ulcers and causes

stomach cancer

GRAM + BACTERIA

Gram Positive Bacteria

◦Can be divided into two groups

◦High G+C ratio

◦Low G+C ratio

◦G = guanine

◦C = cytosineDNA

Research

◦Clostridium

◦Epulopiscium

◦Staphylococcus

◦Lactobacillus

◦Listeria

◦Propionibacterium

◦Leptospira

◦Fusobacterium

◦Where does the bacteria live?◦Shape or arrangement?◦Disease it causes (if it does)?◦Growth conditions?◦ Interesting fact?

Clostridium

Epulopiscium

Staphylococcus

Lactobacillus

Listeria

Propionibacterium

Leptospira

Fusobacterium

DOMAIN ARCHAEA

◦Cell walls lack peptidoglycan (like eukaryotes)

◦Halophiles- organisms that can survive a high salt content

◦Methanogens- organisms that produce methane

◦Hyperthemophiles- organisms that can survive and thrive in high temperatures

MICROBIAL DIVERSITY

◦Though many prokaryotes have

been discovered, scientists have

hardly reached the tip of the

iceberg when it comes to

discovering the vast number of

organisms still out there

◦Maybe YOU will be the next

scientist to discover a new

bacterium!