Sulfate reduction Flashcards
(19 cards)
What is the terminal electron acceptor in sulfate reduction?
Sulfate
What is the end product in sulfate reduction?
Hydrogen sulfide
How good is sulfate reduction for energy production?
Not very good. Its still better than fermentation, but way worse than aerobic respiration
What sort of bacteria have sulfate reduction?
Ones that live in unique environments where better pathways don’t work
What is the first step of sulfate reduction?
Activation of sulfate by adding an ATP to it to form APS
Why does sulfate need to be activated before it can be used for metabolism?
Too stable
Which enzyme catalyzes the first step of sulfate reduction?
ATP sulfurylase
What is the second step of sulfate reduction?
The sulfate reduction. APS is reduced to sulfite by adding 2 electrons and releasing an AMP
Which enzyme catalyzes the reduction of APS to sulfite?
APS reductase
What is the third step of sulfate reduction?
A series of sulfite reductions catalyzed by sulfite reductase
How many electrons get added to sulfate for it to become fully reduced into H2S?
8
What enzyme catalyzes the series of sulfite reductions?
Sulfite reductase
What is the source of electrons in sulfate reduction? How is this different from other metabolic pathways?
Comes from H2 gas or lactate. They come from NADH made in glycolysis and the CAC for the other systems
How are electrons derived from H2 gas for sulfate reduction?
Hydrogenase in the periplasm transfers electrons from H2 to the ETC and releases the protons into the periplasm to form the PMF
How are electrons derived from lactate for sulfate reduction?
Lactate is oxidized to pyruvate by lactate dehydrogenase in the cytoplasm. The pyruvate gets converted to acetate, 1 ATP, CO2 and a bit of H2 gas that goes to hydrogenase
How many ATP does the cell get for using H2 gas as its electron source?
1
How many ATP does the cell get for using H2 gas as its electron source?
2
Where is sulfate commonly found?
Marine sediments and ground water
How does anaerobic corrosion of metal pipes containing iron occur?
H3O+ in the water reacts with Fe2+ in the pipe, which creates small H2 bubbles on the pipe’s surface. The bacteria can use the H2 bubbles and the sulfate in the water to create H2S, which reacts with the iron to form FeS as a precipitate
