Question

BigMoney Inc. has also had a major spill of inorganic H_2 that contaminated the soil around their plant. Scientists at BigMoney have developed mechanisms for removing H^+ from soil, but have not found one for H_2. They want to know, on a strictly theoretical basis (regardless of whether bacteria exist in nature that actually do these specific reactions), if there are any types of bacteria that could metabolize H_2 to give rise to H^+. Please answer a-d below. H_2 rightarrow H^+
a) Is this an oxidation or reduction?
b) H_2 acting as an electron acceptor or donor?
c) Which of the following metabolic pathways (aerobic respiration, anaerobic respiration, aerobic chemolithotrophy and anaerobic chemolithotrophy) could be used to carry out this reaction? Remember, think strictly theoretically. You must think about whether each of these reactions can oxidize or reduce inorganic materials. You may not change the pathways in any manner except the exact molecules that serve as the final electron acceptors and the initial electrons donors; however, the donors and acceptors may NOT change type (organic vs inorganic). For example if a microbe would normally use an organic electron donor and an inorganic electron acceptor, this can NOT change.
d) For each of the pathways that could be used, describe exactly how H^+ will be formed providing the following information:
Is the initial electron donor (from where are the electrons being taken) inorganic or organic?
Which of the pathways discussed in class (glycolysis, TCA, electron transport, chemolithotrophy, photosynthesis, fermentation) will be used to get the electrons?
Is the final electron acceptor organic or inorganic?
Please provide a specific example of a half reaction (either initial donating or final accepting) that would work with the half reaction provided in this scenario, and briefly describe why it was chosen.

Answer 1

Solution :

It is given that BigMoney Inc. had a major spill of an inorganic $H_2$ which contaminated the soil around the plant. The scientist in the BigMoney had developed a mechanism to remove the $H^+$ from the soil but they did not found any for the $H_2$ .

The reaction is : $H_2 \rightarrow H^+$

a). So this is an oxidation reaction as in the reaction the hydrogen atom is removed from the molecule.

b). The $H_2$ acts as an electron donor as it is being oxidized. Any substance that oxidizes is called an electron donor.

c). The above reaction can be carried out by aerobic respiration and the enzyme that is involved is hydrogenase which consumes $H_2$  and it releases a proton out of the cell. The reaction can often occur in our biological cells. This is fermentation that is used in the anaerobic as well as aerobic respiration process.

d). In the production, the electron donor is hydrogen that is organic as the hydrogen will be used from the air or the soil. And the pathways will be chemolithotrophy or fermentation.