A qualitative and quantitative study of the cellular fatty acids of 'Streptococcus milleri' with capillary gas...

Fatty acid analysis was done with GC and GC-MS on 21 strains of 'Streptococcus milleri', representative of the various proposed species. Although no qualitative differences were found in the fatty acid profiles, discriminant analysis of the quantitative data revealed three groups. Streptococcus anginosus and Streptococcus constellatus were indistinguishable but separated from the other two groups which comprised Streptococcus intermedius, with a wide fermentation pattern and Streptococcus intermedius with a narrow fermentation pattern. Three of the strains could be distinguished from the others by a 'fingerprint' of a particularly prominent fatty acid peak. The results support the suggestion that there is more than one species in this group of organisms and that the technique might be of value in epidemiological investigations of 'S. milleri'.