Question

Microbial methane oxidation is an important process because it drastically limits the release of this dangerous greenhouse gas. A group of microbiologists used enrichment cultures of archaea from sediments to obtain two isolates. One oxidized CH₄ to CO₂ using NO₃⁻ as an electron acceptor to generate N₂. The other isolate reduced Fe(III) to Fe(II) during methane oxidation. If you mixed the two isolates with equal amounts of nitrate and Fe(III), which methane-oxidizing archaeon do you think would grow fastest? Why?

Answer 1

Question:

Answer: Fe reducing microbes will grow faster and oxidized the methane very quickly as compared to NO3- reducing species. Because, reduction potential of Fe(+3) to Fe(+2) is +0.74 V but reduction potential of conversation of NO3- to N2 is 1.38 V. Reduction of Fe(+3) is easy and achieve with low potential difference. On the other hand, only single methane will oxidized with reduction of single NO3- molecules. But in other case, for oxidation of 1 methane molecules, 4 molecules of Fe(+3) will reduced. Hence, Fe reducing strain will grow fast in consortium.