Gas Chromatographic Analysis of Cellular Fatty Acids in the Identification of Foodborne Bacteria

Abstract

The cellular fatty acid composition of about 160 strains of Bacillus, lactic acid bacteria, Enterobacteriaceae, and Staphylococcus was analyzed in order to identify foodborne bacteria. In a first step, the reproducibility of the procedure, from the bacterial growth to the extraction and analysis conditions, was evaluated. The stability of fatty acid composition under controlled conditions was confirmed through high similarity levels (So ≥ 94). Secondly, intraspecies similarity was estimated. The existence of low values (So ≤ 79) was demonstrated within each of the four groups of strains investigated, which stressed the importance of analyzing a high number of reference strains in each species. The intraspecies similarity was maximal under optimal growth conditions. Finally, interspecies similarity was compared to intraspecies similarity. The best results of discrimination between species was obtained for the heterogeneous genus Bacillus, for which the 12 species studied could be separated into 6 clusters at a similarity level of 79. The association of 27 species of lactic acid bacteria into 8 clusters should be useful to confirm results of other characterization methods. Only 3 clusters were formed for the 16 Enterobacteriaceae species studied. The genus Salmonella could not be discriminated. The 10 Staphylococcus species were separated into 5 clusters. Coagulase-positive and -negative strains were not differentiated. Since the fatty acid composition did not usually appear specific to single species, characterization of foodborne bacteria by the analysis of their cellular fatty acids should be used to complement other taxonomic methods.

Stability of cyclopropane and conjugated linoleic acids during fatty acid quantification in lactic acid bacteria

“…For many years, FA analysis has been recognized as a useful and rapid tool for the characterization of microorganisms in foods (1,2) and as a complementary analysis to taxonomic classification (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). In addition, knowledge of the FA composition may help to evaluate the nutritional quality of alternative microbiological sources of fats (9,(13)(14)(15)(16)(17).…”

Comparison of Phenotypic and Genotypic Methods Used for the Species Identification of Lactobacillus NP51 and Development of a Strain-Specific PCR Assay

“…Wauthoz et al [57] used GC analysis of cellular fatty acids for the characterization of foodborne bacteria and reported that fatty acid composition usually did not appear unique to a single species itself, so this method should only be used to complement other methods. Yeung et al [60] reported that FAME analysis using the microbial identification system (MIDI) led to very high variability among replicates.…”

Phenotypic characterization of food waste degrading Bacillus strains isolated from aerobic bioreactors

“…In this study B. subtilis and B. licheniformis were allocated in the same group. WAUTHOZ et al (1995) analyzed cellular fatty acids of 160 strains of foodborne bacteria Bacillus (lactic acid bacteria, Enterobacteriaceae and Staphylococcus) and the best results of discrimination between species was obtained for the heterogeneous genus Bacillus, for which 12 species (23 strains) could be separated into 6 clusters at a 79% similarity level. In this work, B. licheniformis, B. pumilus and B. subtilis strains were grouped in the same cluster.…”