Genetic heterogeneities and phenotypic characteristics of strains of the genus Abiotrophia and proposal of Abiotrophia para-adiacens sp nov.

The genus Abiotrophia represents a heterogeneous group of fastidious cocci that show a dependence on pyridoxal hydrochloride analogs for growth. The g enetic heterogeneity in the genus Abiotrophia was examined by DNA-DNA hybri dization, PCR assay of genomic DNA sequences, and restriction fragment leng th polymorphism and sequence homology analyses of the PCR-amplified 16S rRN A gene. Nine type or reference strains of Abiotrophia defectiva, Abiotrophi a adiacens, and Abiotrophia elegans and 36 oral Abiotrophia isolates includ ing the ones presumptively identified as Gemella morbillorum by the rapid I D32 STREP system were divided into four groups: A. defectiva (genotype 1), A. adiacens (genotype 2), A. elegans (genotype 4), and a fourth species (ge notype 3) which we propose be named Abiotrophia para-adiacens sp, nov. A PC R assay specific for detection and identification of the novel Abiotrophia species was developed. A. para-adiacens generally produced beta-glucosidase but did not produce alpha- or beta-galactosidase or arginine dihydrolase, did not ferment, trehalose, pullulan, or tagatose, and was serotype IV, V o r VI. Thus, it was distinguished phenotypically from A. adiacens, A. elegan s, and A. defectiva as well as, apparently, from the recently described spe cies Abiotrophia balaenopterae sp. nov., which produces arginine dihydrolas e and which ferments pullulan but not sucrose (P. A. Lawson et al., Int. J. Syst. Bacteriol. 49:503-506, 1999). Strain ATCC 27527, currently listed as G. morbillorum, was a member of the species A. para-adiacens.