Methanogens and Biogas Production — NEET Biology
✅ Asked in NEET 2025Biogas is a mixture of gases (containing predominantly methane) produced by the microbial activity and which may be used as fuel. You have learnt that microbes produce different types of gaseous end-products during growth and metabolism. The type of the gas produced depends upon the microbes and the organic substrates they utilise. In the examples cited in relation to fermentation of dough, cheese making and production of beverages, the main gas produced was CO₂. However, certain bacteria, which grow anaerobically on cellulosic material, produce large amount of methane along with CO₂ and H₂. These bacteria are collectively called methanogens, and one such common bacterium is Methanobacterium. These bacteria are commonly found in the anaerobic sludge during sewage treatment. These bacteria are also present in the rumen (a part of stomach) of cattle. A lot of cellulosic material present in the food of cattle is also present in the rumen. In rumen, these bacteria help in the breakdown of cellulose and play an important role in the nutrition of cattle. Do you think we, human beings, are able to digest the cellulose present in our foods? Thus, the excreta (dung) of cattle, commonly called gobar, is rich in these bacteria. Dung can be used for generation of biogas, commonly called gobar gas.
NTA tests your understanding of methanogens—bacteria that anaerobically break down cellulose to produce methane-rich biogas. The common trap is confusing methanogens with other fermentation bacteria (like those producing CO₂ in dough/cheese), or forgetting that humans lack these bacteria and cannot digest cellulose. Key points: Methanobacterium lives in cattle rumen and sewage sludge, converts cellulosic waste into fuel through anaerobic respiration, and makes dung valuable for biogas generation. Remember—methane production requires anaerobic conditions and specific bacterial strains, distinguishing it from aerobic fermentation processes you've studied earlier.
What is the major role of methanogens in the rumen of cattle? (NEET 2025)
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