Adaptational changes in cellular phospholipids and fatty acid composition of the food pathogen Listeria monocytogenes as a stress response to disinfectant sanitizer benzalkonium chloride

Aims:  This study provides a first approach to observing the alterations of the cell membrane lipids in the adaptation response of Listeria monocytogenes to the sanitizer benzalkonium chloride. Methods and Results:  A thorough investigation of the composition of polar and neutral lipids from L. monocytogenes grown when exposed to benzalkonium chloride is compared to cells optimally grown. The adaptation mechanism of L. monocytogenes in the presence of benzalkonium chloride caused (i) an increase in saturated-chain fatty acids (mainly C16:0 and C18:0) and unsaturated fatty acids (mainly C16:1 and C18:1) at the expense of branched-chain fatty acids (mainly Ca-15:0 and Ca-17:0) mainly because of neutral fatty acids; (ii) no alteration in the percentage of neutral and polar lipid content among total lipids; (iii) a decrease in lipid phosphorus and (iv) an obvious increase in the anionic phospholipids and a decrease in the amphiphilic phosphoaminolipid. Conclusions:  These lipid changes could lead to decreased membrane fluidity and also to modifications of physicochemical properties of cell surface and thus changes in bacterial adhesion to abiotic surfaces. Significance and Impact of the Study:  The adaptation and resistance of L. monocytogenes to disinfectants is able to change its physiology to allow growth in food-processing plants. Understanding microbial stress response mechanisms would improve the effective use of disinfectants.