A RAPID PROCEDURE FOR THE IDENTIFICATION OF LACTIC-ACID BACTERIA BASED ON THE GAS-CHROMATOGRAPHIC ANALYSIS OF THE CELLULAR FATTY-ACIDS

This study was conducted to develop a rapid numerical procedure for the analysis of gas chromatograms of lactic acid bacteria fatty acid methylesters (FAMEs), along with an examination of some experimental conditions which affect the fatty acid composition of these bacteria. FAME determination was carried out using high resolution gas chromatography (HRGC). Although the nature and the proportion of fatty acids differed among strains, some major components, n-C14:0, n-C16:1, n-C18:1, n-C18:0, and C19 cycl, were found as a group to represent more than 90% of the whole cellular fatty acids. The differences found in the relative composition of the long-chain fatty acids in paired chromatograms were used to calculate a "distance coefficient", based on the differences found for the most important fatty acids, after their prior ranking. The procedure was initially validated with identified species, used as reference strains; then, unknown lactic acid bacteria isolates were compared to these references. The method proved to be useful for rapid comparisons between strains, provided a strict standardization occurred prior to routine application.