hylemonella hylemonella hydrogenophaga is a genus of bacteria from the family of comamonadaceae with one known species (hylemonella gracilis). hylemonella gracilis has been isolated from pondwater. hylemonella scientific classification domain: bacteria phylum: pseudomonadota class: betaproteobacteria order: burkholderiales family: comamonadaceae genus: hylemonellaspring et al. 2004 species h. gracilis