BIOCHEMICAL AND GENETIC-CHARACTERIZATION OF A PREVOTELLA INTERMEDIA NIGRESCENS-LIKE ORGANISM/

Thirty-three previously non-typable faintly pigmented Gram-negative an aerobic bacterial isolates, biochemically most closely related to Prev otella intermedia and Prevotella nigrescens, were analysed for enzymic reactions, cellular fatty acid (CFA) composition, electrophoretic mob ility of malate and glutamate dehydrogenases, hybridization with P. in termedia and P. nigrescens species-specific oligonucleotide probes and , for genetic heterogeneity, by arbitrarily primed PCR (AP-PCR). P. in termedia ATCC 25611(T) and P. nigrescens ATCC 33563(T) were run in par allel for comparison. Twenty-nine isolates originated from the normal oral flora of 18 subjects (including five mother-child pairs), and fou r isolates from various infections, Except for a negative lipase react ion, enzymic profiles of the test isolates were similar to those of P. intermedia and P. nigrescens. Clustering of CFAs, electrophoretic mob ility patterns, hybridization with DNA probes for P. intermedia and P. nigrescens, and AP-PCR band patterns of the test isolates differed fr om those of the type strains of P. intermedia and P. nigrescens, sugge sting the existence, in humans, of a new anaerobic species of pigmente d, moderately saccharolytic, indole-positive Cram-negative rods.