Identification of indole producing black-bigmented rods resembling Prevotella malaninogenica

Abstract

We recently isolated a few anaerobic gram-negative, black-pigmented rods from saliva and periapical lesions. Several of these isolates, although resembling Prevotella melaninogenica, P. denticola or P. loescheii in most of their phenotypic expression, were capable of producing indole, a biochemical characteristic atypical of the P. melaninogenica group. Enzyme patterns by the API ZYM system and protein bands on SDS-PAGE gels were useful in differentiating the above three Prevotella species from other black-pigmented Prevotella, and in differentiating P. loescheii from P. melaninogenica and P. denticola. We failed to find phenotypic characteristics for differentiating P. melaninogenica and P. denticola. DNA-DNA hybridization is thus necessary for identification of the two Prevotella species.