Differentiation of bacteria using fatty acid profiles from gas chromatography–tandem mass spectrometry

Abstract

Fatty acids are essential components in cell membranes of bacteria, and they determine the different structures of lipids and lipid A. Therefore, fatty acids are good targets for development of rapid and reliable methods for differentiation of bacteria. Here we report fatty acid distributions in three different bacteria-Escherichia coli, Francisella novicida and Bacillus subtilis-studied by using gas chromatography-tandem mass spectrometry. Different fatty acid profiles were observed in the three bacteria. Hydroxyl fatty acids were observed in E. coli and F. novicida, but not in B. subtilis. Carbocyclic fatty acids were observed in E. coli but not in F. novicida or B. subtilis. Methyl-branched fatty acids were observed in B. subtilis but not in E. coli or F. novicida. Although saturated and unsaturated fatty acids were all observed in the three bacteria, their chain lengths and distribution patterns were different. The results indicate that the fatty acid profile in a given bacterium is highly specific, and gas chromatography-tandem mass spectrometry is a rapid and sensitive method for the identification or detection of bacteria.