Properties of oral asaccharolytic black-pigmented Bacteroides

Bacteroides endodontalis, a newly described asaccharolytic black-pigmented Bacteroides, along with the other two recognized species of this group (B. gingivalis and B. asaccharolyticus) were studied for their susceptibility to various dyes and inhibitory agents and for some of their enzymatic activities to facilitate differentiating between them. Bacteroides endodontalis resembles B. asaccharolyticus physiologically except for the fact that the former cannot grow on media containing methylene blue, neutral red, or 3% sodium chloride, whereas B. asaccharolyticus can. On the other hand, B. endodontalis and B. gingivalis can grow on a medium containing Congo red while B. asaccharolyticus cannot.