ch 15 microbio eco diversity in bacteria

3 reasons for microbial diversity

metabolic, ecological and phylogenetic.

Why the three reasons are shared

gene loss, convergent evolution and horizontal gene transfer

cyanobacteria structure

hormogonia: short and motile filaments, dispersal

akinetes: resting structure protect organism from cold and desiccation

purple sulfur bacteria 

H2S=electron donor making it anaerobic, salt marshes, purple=carotenoids 

purple nonsulfur bacteria

synthesize carotenoids=a lot of colors, photoheterotrophs, calvin cylce for CO2 fix

green sulfur bacteria

Chlorobi, anaerobic anoxygenic phototroph, H2S>SO4 reverse TCA cycle, use chlorosomes, nonmotile 

green nonsulfur bacteria

chloroflexi, H2 or H2S for electron donor, gliding motility 

nitrogen fixation reguires 

nitrogenase and ATP

Diazotrophs fix

N2 into NH3

symbiotic diazotrophs

rhizobia, provides nitrogen for host, host provides carbon source

free living diazotrophs

must protect nitrogenase from oxygen, grow anoxically or fix N2 when O2 low or not present. 

Denitrifiers

turn nitrate/nitrite to gas state nitrogen

nitrifiers

oxidize NH3 and nitrite to nitrate

nitrogen reducers

reduce nitrate to nitrite

nitrification: ammonia oxidizers

oxidize ammonia to nitrite

nitrification: nitrite oxidizer 

oxidize nitrite to nitrate 

Dissimilatative sulfur oxidizers 

conserve energy through reduction sulfur compounds, calvin cylce in carboxysomes

Dissimilatative iron reducers

oxidation of H2 to reduce iron/manganese

microbial predators: predation methods

invade and replicate in cytoplasm, attach to cell surface and drink up nutrients from peri or cytoplasm

Bdellovibrio

bean shape, motile and eats cytoplasm contents, PREDATION NOT OBLIGATORY

Spirochetes

gram (-), motile, endoflagella, flexible

budding division

unequal cell growth, new daughter cell, polar growth

prosthecate

increase surface to volume ration, stops from sinking into anoxic zone, stalk/hyphae

caulobacter

prostheca, uequal binary fission