Fibrobacterota is a small bacterial phylum which includes many of the major rumen bacteria, allowing for the degradation of plant-based cellulose in ruminant animals.

[2] Although Fibrobacterota is currently recognized as a distinct phylum, phylogenetic studies based RpoC and Gyrase B protein sequences, indicate that Fibrobacter succinogenes is closely related to the species from the phyla Bacteroidetes and Chlorobi.

[5] All of these results provide compelling evidence that the species from these three phyla shared a common ancestor exclusive of all other bacteria and it has been proposed that they should all recognized as part of a single “FCB”superphylum.

Fibromonas termitidis" F. elongatus F. succinogenes H. succinigenes H. porci Fibrobacter intestinalis The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LSPN)[12] and the National Center for Biotechnology Information (NCBI).

[18] The predominance of subphylum 2 in cellulolytic fibre-associated bacterial communities in hindguts of wood-feeding Nasutitermes corniger suggests that they play an important role in the breakdown of plant material in higher termites.