Below is a table of standard reduction potentials for reactions important to biological systems. Use this to answer the following questions.
Eo'
2H+ + 2e- --> H2
-0.42
NAD+ + 2H+ + 2e- --> NADH + H+
-0.32
So + 2H+ + 2e- --> H2S
-0.27
FAD + 2H+ + 2e- --> FADH2
-0.22
SO42- + 8H+ + 6e --> So + 4H2O
-0.20
NO3- + 2H+ + 2e- --> NO2- + H2O
0.42
NO2- + 8H+ + 6e- --> NH4+ + 2H2O
0.44
Fe3+ + e- --> Fe2+
0.77
O2 + 4H+ + 4e- --> 2H2O
0.82
Part A. Thiobacillus denitrificans couples oxidation of elemental sulfur to reduction of nitrate. Write the two half reactions that describe this process.
Part B. Would this occur under aerobic or anaerobic conditions? Explain why this is the likely case.
Part C. Would these microbes likely be autotrophs or heterotrophs?
Part D. This microbe has a very long generation time, on the order of several hours. Give two reasons why this microbe grows so slowly.
Below is a table of standard reduction potentials for reactions important to biological systems. Use this to answer the following questions.
| Eo' | |
| 2H+ + 2e- --> H2 | -0.42 |
| NAD+ + 2H+ + 2e- --> NADH + H+ | -0.32 |
| So + 2H+ + 2e- --> H2S | -0.27 |
| FAD + 2H+ + 2e- --> FADH2 | -0.22 |
| SO42- + 8H+ + 6e --> So + 4H2O | -0.20 |
| NO3- + 2H+ + 2e- --> NO2- + H2O | 0.42 |
| NO2- + 8H+ + 6e- --> NH4+ + 2H2O | 0.44 |
| Fe3+ + e- --> Fe2+ | 0.77 |
| O2 + 4H+ + 4e- --> 2H2O | 0.82 |
Part A. Thiobacillus denitrificans couples oxidation of elemental sulfur to reduction of nitrate. Write the two half reactions that describe this process.
Part B. Would this occur under aerobic or anaerobic conditions? Explain why this is the likely case.
Part C. Would these microbes likely be autotrophs or heterotrophs?
Part D. This microbe has a very long generation time, on the order of several hours. Give two reasons why this microbe grows so slowly.
