Microbes In Human Welfare

Biogas is a mixture of gases, predominantly methane, produced when microbes anaerobically digest organic waste such as cattle dung (gobar), and the organisms chiefly responsible for methane production are the methanogens, a group of archaebacteria. These methanogens, such as Methanobacterium, thrive in oxygen-free environments like the anaerobic sludge of biogas plants and also inhabit the rumen of cattle, where they act on cellulosic material to release methane that becomes part of the cattle dung used as feedstock. Cyanobacteria are incorrect because they are photosynthetic, nitrogen-fixing organisms that produce oxygen, not the anaerobic methane producers required here. Lactic acid bacteria are wrong because they ferment sugars into lactic acid, as in curd formation, and do not generate the combustible methane of biogas. Mycorrhizal fungi are incorrect since they form symbiotic associations with plant roots to aid mineral absorption and have no role in biogas production. As described in NCERT Class 12, Chapter 10 (Microbes in Human Welfare), the technology of biogas production was developed largely by IARI and KVIC. As a biological consistency check, only methanogens combine anaerobic metabolism with methane output, confirming them as the correct microbial group.