Bacteroides is a genus of gram-negative bacteria. "Bacteroides" species are non-endospore-forming, anaerobes, and may be either motile or non-motile, depending on the species. The DNA base composition is 40-48% GC. Unusual in bacterial organisms, "Bacteroides" membranes contain sphingolipids. They also contain meso-diaminopimelic acid in their peptidoglycan layer.