Identification of monounsaturated fatty acids of Aerococcus viridans with dimethyl disulfide derivatives and combined gas chromatography-mass spectrometry

Abstract

Location of the bouble-bond position of monounsaturated fatty acids of Aerococcus viridans was accomplished by combined gas chromatography (GC)-mass spectrometry analysis of dimethyl disulfide (DMDS) derivatives. The monoenoic fatty acids from whole bacterial cells wer converted to methyl esters and then to DMDS adducts and analyzed by capillary GC-mass spectrometry. The mass spectra of DMDS adducts gave an easily recognizable molecular ion (M+) and two major diagnostic ions attributable to fragmentation between the two CH3S groups located at the original site of unsaturation. Two relatively noverl acids that distinguish aerococci from bacteria of closely related genera were identified as C(16:1) ω9c and C(16:1) ω9t from their mass spectrometry fragmentation patterns and retention characteristics on nonpolar capillary GC columns