Corynebacterium freneyi sp nov., alpha-glucosidase-positive strains related to Corynebacterium xerosis

Three coryneform strains from clinical specimens were studied. They belonge d to the genus Corynebacterium, since they had type IV cell walls containin g corynemycolic acids. They had phenotypic characteristics that included al pha -glucosidase, pyrazinamidase and alkaline phosphatase activities and fe rmentation of glucose, ribose, maltose and sucrose. These are the character istics of Corynebacterium xerosis. Since this species is very rare in human pathology, the strains were studied in more detail by comparing the 16S-23 S intergenic spacers, rDNA sequences and levels of DNA similarity of these three strains and those of the reference strains C. xerosis ATCC 373(T) and Corynebacterium amycolatum CIP 103452(T). According to DNA-DNA hybridizati on data, the three novel strains are members of the same species (level of DNA similarity > 72%). Phyllogenetic analysis revealed that these strains a re closely related to C. xerosis and C. amycolatum, but DNA-relatedness exp eriments showed clearly that they constitute a distinct new species, with l evels of DNA relatedness of less than 23% to C. xerosis ATCC 373(T) and les s than 5% to C. amycolatum CIP 103452(T). Two other alpha -glucosidase-posi tive strains presenting the same biochemical characteristics were included in the study and proved to be C. amycolatum. This new species can be differ entiated from C. xerosis and C. amycolatum strains by carbon source utiliza tion, intergenic spacer region length profiles and some biochemical charact eristics such as glucose fermentation at 42 degreesC and growth at 20 degre esC. The name Corynebacterium freneyi sp. nov. is proposed.