Proposal of a new species Prevotella nigrescens sp. nov. among strains previously classified as Pr. intermedia.

Thirty-one strains characterized initially as Prevotella inter-media were subjected to: DNADNA hybridization, against reference DNA probes from strains ATCC 25611T and ATCC 33563; physiological tests; peptidase and lipase activities; and multilocus enzyme analysis using malate dehydrogenase (MDH) and glutamate dehydrogenase (GDH). In keeping with the properties of Pr. intermedia, all strains fermented glucose and sucrose, hydrolyzed starch but not aesculin and produced indole, acetic, isobutyric and isovaleric acids as metabolic end products. Under stringent hybridization conditions, DNA reassociation with the reference probe was higher than 70% (72-98%) or low (< 20%), and permitted the delineation of strains into two well-defined