B. acidifaciens
B. distasonis (reclassified as Parabacteroides distasonis) 
B. gracilis
B. fragilis
B. oris
B. ovatus
B. putredinis
B. pyogenes
B. stercoris
B. suis
B. tectus
B. thetaiotaomicron
B. vulgatus
etc.<unk>  is a genus of Gram-negative, rod-shaped<unk> eria.<unk>  species are non-endospore-forming, anaerobes, and may either be motile or non-motile, depending on the species. The DNA base composition is 40-48% GC. Unusual in<unk> erial organisms,<unk>  membranes contain sphingolipids. They also contain meso-diaminopimelic acid in their peptidoglycan layer.<unk>  are normally commensal, making up the most substantial portion of the mammalian gastrointestinal flora, where they play a fundamental role in processing of complex molecules to simpler ones in the host intestine. As many as 1010-1011 cells per gram of human feces have been reported. They can use simple sugars when available, but the main source of energy is polysaccharides from plant sources.
Bacteroides
Lactobacillus
Arcobacter
Streptococcus
Coccus
Salmonella
Pseudomonas
Helicobacter