substrates? H subscript 2 S?

Question

I cannot get this one for nothing and i have read this section over and over.

Distinguish between the types of substrates available to cells for H subscript 2 S production.?

Answer 1

H2S can be generated by two different processes:
1. decomposition of sulfur-containing organic compounds by microorganisms.

2. direct formation of H2S from sulfate. This process is carried out by the sulfate-reducing bacteria, which are obligate anaerobes. These bacteria oxidize organic compounds and molecular hydrogen by using sulfate as an oxidizing agent.