Effect of the fatty acid composition of acclimated oenological Lactobacillus plantarum on the resistance to ethanol

The aim of this work was to evaluate the changes due to acclimation to ethanol on the fatty acid composition of three oenological Lactobacillus plantarum strains and their effect on the resistance to ethanol and malic acid consumption (MAC). Lactobacillus plantarum UNQLp 133, UNQLp 65.3 and UNQLp 155 were acclimated in the presence of 6 or 10% v/v ethanol, for 48h at 28 degrees C. Lipids were extracted to obtain fatty acid methyl esters and analysed by gas chromatography interfaced with mass spectroscopy. The influence of change in fatty acid composition on the viability and MAC in synthetic wine was analysed by determining the Pearson correlation coefficient. Acclimated strains showed a significant change in the fatty composition with regard to thenonacclimated strains. Adaptation to ethanol led to a decrease in the unsaturated/saturated ratio, mainly resulting from an increase in the contribution of short-length fatty acid C12:0 and a decrease of C18:1. Thecontent of C12:0 was related to a higher viability after inoculation of synthetic wine. The MAC increased at higher contents in saturated fatty acid, but its efficiency was strain dependent. Significance and Impact of the StudyUnderstanding the adaptation of oenological strains to ethanol has strong impact on winemaking as it allows defining the most appropriate conditions to maintain bacteria viability and improve the efficiency of malolactic fermentation. The acclimation of oenological Lact.plantarum in media containing ethanol produces a drastic decrease of C18:1 with an increase in the content of saturated short-chain-length membrane fatty acids that are correlated with a higher resistance to the adverse environmental conditions of wine.