||Caption: Cellulose degrading rumen bacterium Fibrobacter succinogenes. Fibrobacter succinogenes, also known as Bacteroides succinogenes, is one of the most important cellulolytic bacterium (cellulose degrading bacteria) in animal intestinal tracts (rumen). Cows, like all herbivorous ruminant animals, have a complex stomach divided into chambers. One such chamber is the rumen that contains rumen bacteria. In the rumen bacteria live symbiotically in large numbers and serve to break down cellulose in plants, making plant matter digestible. F. succinogenes actively adheres to cellulose. F. succinogenes produces both a series of cellulose-binding proteins, some of which have endoglucanase activity and a thin glycoprotein glycocalyx that results in strong adhesion to cellulose. Fibrobacter spp. are rod shaped, obligate anaerobic, gram-negative, saccharolytic bacteria. The main by-products of their anaerobic respiration are acetic acid, iso-valeric acid, and succinic acid. Methane is also produced in the rumen. The major precursor of the methane formed in the rumen is hydrogen. This hydrogen is produced during the fermentation of feed by the rumen microbial community and is used by methanogenic bacteria to produce methane.