cetobacterium cetobacterium cetobacterium is a gram-negative, pleomorphic, non-spore-forming, rod-shaped and non-motile genus of bacteria from the family of fusobacteriaceae. cetobacterium scientific classification domain: bacteria phylum: fusobacteriota class: fusobacteriia order: fusobacteriales family: fusobacteriaceae genus: cetobacteriumfoster et al. 1996 type species cetobacterium ceti species c. ceti c. somerae