Module 7 -> Bacterial MVPs

Proteobacteria

Very metabolically diverse

Purple Bacteria

phototrophic bacteria

Purple Sulfur bacteria

Anoxygenic photosynthesis → do not make oxygen

Use sulfur as source of electrons

Mixotrophic growth → organic or CO2 as carbon source

What pigments allow anoxygenic photosynthesis in purple bacteria

Bacteriochlorophylls & Carotenoid pigments within the intracytoplasmic membranes

Methylotrophs

Can oxidize on-carbon compounds (no c-c bonds)

Methanotrophs

Methylotrophs that use methane as their carbon source

Obligate aerobes

Enzyme that allows methanotrophs to oxidize methane

methane monooxygenase (MMO)

Nitrifiers

Chemolithoautotrophs

Use ammonia as energy and electrons converting it to nitrite

enzyme that allows ammonia oxidizers to oxidize ammonia

ammonia monooxygenase (AMO)

Enzyme found in nitrite oxidizers

Nitrite oxidoreductase (Nxr)

Pseudomonads

Aerobic chemoorganoheterotrophs

Polar flagella

Siderophore is produced by what group of bacteria and what is it

Pyoverdin (fluorescent) used to acquire iron from environment

Pseudomonads

Free-living N2-fixing bacteria mechanism to protect from excess oxygen

Thick capsule around the cell restricting the flow of oxygen into the cytoplasmic space

Some can be anaerobic and in non-oxygen rich environments

Alphaproteobacteria - Symbiotic N2-fixing bacteria

Aerobic gram-negative rods

Agrobacterium

Rhizobia

Parasitic relationship with plants → crown gall disease

Oncogenes from Agrobacterium

Cancer causing genes causing uncontrolled/cancerous growth of the plant

Opines from Agrobacterium

Unique amino acids

Rhizobium

alphaproteobacteria

root nodules

mutualists form symbiotic relationships with legumes, fixing atmospheric nitrogen in root nodules.

How do legumes form root nodules

1. Flavonoids produced by root signals to rhizobia

2. Express nod (nodulation) genes

3. Produces a nod factor to indicate to the plant that it is a good partner for the mutualism

4. Plant curls root into a shepherds crook where bacteria can infect

5. Infect with infection thread where bacteria divides on

6. Nodule forms due to repeated bacterial cell division

Leghemoglobin

Carries oxygen to rhizobia provided a controlled mechanism to deliver oxygen for respiration

Enteric Bacteria

Gammaproteobacteria

Facultative anaerobes

Oxidase negative but has cytochrome A → ETC

Peritrichous flagella

Deltaproteobacteria

Gram-negative and most aerobic

Bdellovibrio

Deltaproteobacteria

preys on other gram-negatives by invading their periplasmic space, leading to cell lysis.

Process of bdellovibrio life cycle

1. Seek host

2. Strike, burrow into outer membrane into periplasmic space releasing hydrolytic enzymes

3. Cell wall degradation becoming spherical (bdelloplast/spheroplast)

4. Consumes cytoplasm

5. Bedellovirbro elongates, divides, and lyses the host cell to release new bdellovibrio.

Gliding Myxobacteria

Deltaproteobacteria

Complex with a huge amount of chromosomes

How do myxobacteria hunt?

1. hunt and lyse while communicating with each other

2. follow slime trails

3. When encounters prey, they begin rippling caused by cells moving forward and backwards over their prey, lysing, killing and absorbing nutrients

What do myxobacteria do in absence of prey

Form multicellular fruiting bodies to distribute their cells to other environments

• filled with myxospores

Firmicutes

Gram-positive Bacteria

Low G+C content of DNA

Actinobacteria

Gram-positive bacteria

high G+C content of DNA

Similarities between Staphylococcus and Micrococcus

Aerobic metabolisms

• catalase positive

Resistant to desiccation and tolerant to high salt conc

Pigmentation

Lactic Acid Bacteria

Non-spore forming gram-positive organisms within firmicutes

Homofermenters

Only produce lactic acid

Heterofermenters

Make a variety of different end products

Streptococcus pyogenes

Causative agent of necrotizing fasciitis - flesh eating disease

Streptococcus pneumoniae

Causative agent of pneumonia and ‘strep thoat’

Bacillus genus

• Members of firmicutes

• facultatively anaerobic or obligate aerobes

• can form spores

Clostridium group

• Members of firmicutes

• Strict anaerobes

What is the bacillus group good at

degrading polymers

produce antibiotics

bacillus anthracis

anthrax

bacillus thuringiensis

Active against insect larvae

What is bacillus thuringiensis toxin made of

• endospore is surrounded by parasporal body

• Will produce crystalline protoxin

protoxin

toxic when cleaved

parasporal body

larger spore bodies

Clostridium botulinum

produces botulinum toxin which is dangerous to inhale or ingest at low doses

• also is botox

Mycobacterium

Actinobacteria

• cell walks contain mycolic acids

  • resistant to many chemicals

Mycobacterium tuberculosis

tuberculosis

mycobacterium leprae

leprosy

Filamentous actinobacteria

• form branching mycelia

• form condira

• produce geosmins

• Produce antibiotics

What genus is important in filamentous actinobacteria

streptomyces → important for antibiotics

mycelia

filamentous actinobacteria grow as branching mycelia

Conidia

desiccation-resistant spores produced by filamentous actinobacteria

where are conidia produced

sporophores

Geosmins

terpine compounds released when spores are produced by actinobacteria

Cyanobacteria

• gram-negative

• oxygenic phototrophs

What is stored within thylakoid membranes?

chlorophylls and phycobilins

heterocyst

Structures where cyanobacteria fix nitrogen