parabacteroides acidifaciens parabacteroides acidifaciens parabacteroides acidifaciens is a gram-negative, anaerobic, non-spore-forming, rod-shaped and non-motile bacterium from the genus of parabacteroides which has been isolated from human faeces. parabacteroides acidifaciens scientific classification domain: bacteria phylum: bacteroidota class: bacteroidia order: bacteroidales family: "tannerellaceae" genus: parabacteroides species: p. acidifaciens binomial name parabacteroides acidifacienswang et al. 2019 type strain 426-9