Fatty acid membrane composition and activation of glycine-betaine transport in Lactococcus lactis subjected to osmotic stress

Lactococcus lactis subsp. cremoris NCDO763 accumulates glycine-betaine (bet aine) when submitted to an osmotic stress with NaCl. Betaine transport acti vity increases with the extent of the osmotic upshock but also with growth temperature, and supplementation of the medium by Tween-80. Fatty acid anal ysis of the lipid fraction of L. lactis NCDO763 reveals significant modific ations of the fatty acid composition of the membrane when cells are submitt ed to osmotic stress, high temperature or Tween-80 medium supplementation. The main modification in L. lactis membrane fatty acid composition in respo nse to high osmolality is the increase of Cyclopropane Fatty Acid (CFA) Del ta C19:0, whereas Unsaturated/Saturated ratio remains unchanged. (C) 2000 E lsevier Science B.V. All rights reserved.