Methanogens and Homoacetogens

Question 1

What do methanogens do?

Answer 1

make methane

Question 2

Methanogens are found in what environment

Answer 2

anoxic
temperature does not matter

Question 3

What type of carbon do methanogens use as PEDs

Answer 3

2 of 3 classes use small organic like acetate (hetero) and 1 class uses inorganic (litho) (H2)

Question 4

what group of microbes have syntrophic relationship with methanogens

Answer 4

homoacetogens

Question 5

Homoacetogen

Answer 5

Makes acetate

Question 6

What do homoacetogens use for TEA

Answer 6

mostly respiration (external inorganic) but can ferment (internal organic)

Question 7

what is main ecological impact of homoacetogens

Answer 7

reducing inorganic C
(but can also reduce Nitrate and thiosulfate

Question 8

Anaerobic decomposition

Answer 8

incomplete breakdown of organic carbon in absence of oxygen, resulting in methane

Question 9

simplified anaerobic decomposition

Answer 9

1) organic macromolecules broken down into smaller organics by hydrolytic bacteria
2) small organics broken down into CO2, H2, by fermenters
3) CO2 and H2 formed into acetate by homoacetogens
4) acetate broken down into methane by methanogens

Question 10

PEDs for homoacetogens

Answer 10

H2 (when lithotrophically)
fermentation of larger organics like fatty acids