L4.3 Sulfur and Nitrogen Cycles

Question 1

Where can sulfur-utilizing bacteria commonly found?

Answer 1

Inactive volcanoes

Question 2

Four groups associated with the sulfur cycle?

Answer 2

1. Dissimilatory Sulfate-Reducing
2. Dissimilatory Sulfur- Reducing
3. Dissimilatory Sulfur-Oxidizing Bacteria
4. Assimilatory Sulfate-Reducing Bacteria

Question 3

Dissimilatory Sulfate-Reducing bacteria
Key genera

Answer 3

Desulfovibrio, Desulfobacter
- obligate anaerobe (electron acceptor) along with hydrogen as e- donor

• global sulfur cycle but also causes spoilage in canned foods through hydrogen sulfide gas

Question 4

explain the pathway of dissimilatory sulfate bacteria

Answer 4

• Sulfate to adenosine-5-sulfate (APS) using SAT
• APS to sulfide through AprAB

Question 5

Dissimilatory Sulfur-Reducing Bacteria

key genera and characteristics

Answer 5

Desulfuromonas, Wolinella, Sulfolobus

-facultatively aerobic,

• use sulfur as electron acceptor
• they co-exist with H2S bacteria to create anoxic sulfur cycle in marine sediments

Question 6

Dissimilatory Sulfur-Oxidizing Bacteria

key genera and characteristics

Answer 6

Thiobacillus, Achromatium, Beggiatoa
- oxic environment near H2S sources (springs, hydrothermal vents)
- O2 as terminal e- acceptor
-obligate/facultative chemolithotrophs
- they get electrons from sulfur as their adaptation

Question 7

oxidize ferrous iron

Answer 7

Thiobacilus

Question 8

large size, internal storage of sulfur granules

Answer 8

Achromatium