DIFFERENTIATION BETWEEN YEAST SPECIES, AND STRAINS WITHIN A SPECIES, BY CELLULAR FATTY-ACID ANALYSIS .5. A FEASIBLE TECHNIQUE

The cellular long-chain fatty acids (FA's) of 58 strains representing 16 yeast species were examined by capillary gas chromatography (GC) on a polar column. Many of the yeast strains selected for examination in this study did not grow, or grew very poorly, under the cultivation parameters applied. This indicated that all yeasts cannot be cultivated under a single set of rigidly standardised cultivation parameters. The variation between relative percentages (RP's) of C18:1, C18:2, and C18:3 in replicate cultivations of the same strain was often unacceptably high. In most cases this variation was reduced to acceptable levels upon recultivation of the organism. This implicated the batch culture process as possible source of the variation. The yeast cellular acid profile (CFAP) is clearly more complex than recognised previously. Some yeasts contained at least four dienoic and two trienoic FA's, whilst other species contained three delta-11 monoenoic FA's. The presence of C17:1(8) in all yeasts studied was confirmed by interpretation of picolinyl ester-mass spectra. Minor FA's were again proved to be extremely important when attempting to differentiate between yeast species by means of cellular fatty acid analysis (CFAA). Although data were limited, it seems likely that CFAA will be able to differentiate between a number of Kluyveromyces spp. Torulaspora spp. had unique CFAP's amongst the species studied here. Integration of FA-data from this paper with data from our previous papers indicated some overlap between the CFAP's of Saccharomyces spp. and Kluyveromyces spp. These facts indicate that CFAA is not a generally applicable yeast identification technique. It is, however, an easily applied, reliable method to characterise yeast strains in a variety of species.