Ch 14.4-14.6 (Book) Flashcards
obligate aerobe
bacteria that only grow using O2 as the TEA
anaerobic respiration
using TEA other than O2
ex. nitrogen, sulfur, metal, chlorinated organics
E. coli different terminal oxidoreductases
allow reduction of alternative TEA
trimethylamine
causes fishy odor
reduced by bacteria
are there different initial substrate oxidoreductases?
yes, receive e- from different organic donors
do bacteria use the strongest e- donor and strongest acceptors available?
yes
which type of bacteria often utilize nitrogen and sulfur
soil bacteria
dissimilatory denitrification
reduction of nitrogen for energy yield
ammonia used for respiration
assimilatory nitrification
reduction of nitrate to ammonia for building biomass
sequence of nitrate reduction
nitrate –> nitrite –> nitric oxide –> nitrous oxide –> nitrogen gas
or nitrate –> ammonia + water
sequence of sulfur reduction
sulfate –> sulfite –> thiosulfate –> sulfur –> hydrogen sulfate
dissimilatory metal reduction
reducing metals as TEA
can be used for making electricity in a battery
ex. iron, magnesium
reduced minerals and single-carbon compounds serve as e- donors to the ETS in which type of metabolism?
lithotrophy/chemolithotrophy
is the TEA in lithotrophy a strong oxidant?
yes because most inorganic substrates are poor e- donors compared to glucose
TEA ex. O2, NO3-, Fe3+
obligate lithotroph
consume no organic carbon source
build biomass by fixing CO2
iron oxidation lithotrophy
reduced metal ions like Fe2+ get oxidized to provide energy
this generates metals with higher oxidation states (Fe3+) that other bacteria use for anaerobic respiration
where does iron oxidation happen
low pH like in mines where other microbes oxidize sulfur to sulfuric acid
rusticyanin
a periplasmic protein that collects e- and excludes the metal itself
reverse electron flow
an e- donor reduces an ETS with an unfavorable reduction potential using deltapH as energy source
nitrogen oxidation lithotrophy pathway
ammonium –> hydroxylamine –> nitrite –> nitrate