The bacterias needed to digest the organic materials and transform it into methane gas only thrives in anaerobic conditions, this means without the presence of air. In fact this is what makes bio-digesters good when dealing with waste excrements, because the bacterias don't survive if exposed to air.
Probably anaerobic conditions.
It can live in both aerobic and anaerobic conditions . So , basically it is both ...!
cellular respiration,aerobic:fermentation,anaerobic
anaerobic conditions
Diplomonads and parabasalids are two groups that have adapted to anaerobic conditions.
Proteus can grow in anaerobic conditions due to the fact that it is a facultative anaerobe. It can also, however, grow in oxygenated conditions for the same reason.
Lactic acid
fermentation
Fermintation
Many types of bacteria can live in Anaerobic conditions, I.e they don't need oxygen to live, as they create energy using anaerobic respiration.
Under anaerobic conditions
skeletal muscle