Which bacterium is typically found in the rumen of cattle?

Methanobacterium

The correct answer is Option (3)-Methanobacterium.

The rumen is the largest compartment of the cow's stomach and is responsible for the initial digestion of plant-based feed. It is a specialized fermentation chamber where complex carbohydrates, such as cellulose and hemicellulose, are broken down by microbial activity.

Methanobacterium 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. 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. The presence of Methanobacterium in the rumen is significant because it contributes to the overall fermentation process and energy metabolism of the cow.