Solution

In a gobar gas (biogas) plant, cattle dung is digested anaerobically by bacteria.
In the final stage, methanogenic bacteria (methanogens) such as Methanobacterium convert the products into methane ($CH_4$), the main fuel gas of biogas, along with $CO_2$.
Methanogens are also present in the rumen of cattle, so dung is rich in them.
So methanogens are utilised in the gobar gas plant.

Concept Methanogens produce methane

Microbes in production of biogas in past papers

4 questions from this chapter have appeared across 4 exam years.