Fatty acid profiles of Vibrio parahaemolyticus and its changes with environment.

The fatty acid (FA) profiles of 15 strains representing four genera (Vibrio, Pseudomonas, Aeromonas, and Shewanella) and seven species were compared by capillary gas chromatography with flame ionization detection. FA fingerprints of Vibrio parahaemolyticus were established by similarity calculation and principle component analysis. This provided a simple measure for distinguishing V. parahaemolyticus from other bacteria. The similarity scores indicated by correlation coefficient and vector cosine were divided into three regions and suggested that the strains with scores higher than 0.980 probably belonged to V. parahaemolyticus. However, samples with low scores (<0.850) were classified under other genera. Furthermore, the alterations in FA profiles of V. parahaemolyticus in the presence of various environmental pressures were investigated. The production of saturated FA (SFA) increased gradually concomitant with a decreased proportion of unsaturated FA (UFA) with rising temperature. Similarly, the SFA tended to increase at the expense of UFA with prolonged culture time. In addition, V. parahaemolyticus changed its FA profiles to contain increased short-chained FA to resist an acidic environment, whereas alkaline conditions stimulated high production of long-chained FA. Analysis on FA profile is valuable for the physiological study of V. parahaemolyticus and its rapid identification.
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