A NUMERICAL TAXONOMIC STUDY OF STREPTOCOCCUS-SANGUIS, S-MITIS AND SIMILAR ORGANISMS USING CONVENTIONAL TESTS AND PYROLYSIS MASS-SPECTROMETRY

Numerical taxonomic methods were applied to the results of pyrolysis m ass spectrometry (Py-MS) and conventional test reaction patterns (CTRP s) obtained with 46 strains of oral streptococci identified as represe ntative of six species. Of these: Streptococcus gordonii strains forme d a single homogeneous well-differentiated cluster both in the Py-MS a nd CTRP analyses; S. oralis strains were more diverse, forming 2 CTRP and 3 Py-MS clusters; S. crista, S. parasanguis and S. sanguis formed clear, but diverse and poorly differentiated clusters on the basis of CTRPs, and were poorly differentiated in the Py-MS analysis; and S. mi tis strains were clearly diverse in both analyses. Peritrichously fimb riate ('tufted') S. mitis strains formed a tight cluster, well differe ntiated from the type strain in both Py-MS and CTRP analyses, and may represent a previously unrecognised centre of variation.