Changes in membrane lipid composition of Clostridium acetobutylicum during acetone-butanol fermentation: Effects of solvents, growth temperature and pH

Abstract

Changes in membrane lipid composition of Clostridium acetobutylicum were studied during acetone-butanol fermentation. Large changes were found in phospholipid composition and in fatty acid composition, the latter characterized mainly by a decrease in the unsaturated/saturated fatty acid (U/S) ratio. The effects of the addition of alcohols (ethanol, butanol, hexanol and octanol) and of acetone were also studied. In all cases, large changes were observed in the U/S ratio but with differences which were related to the chain lengths of the alcohols. The effect of solvents appears to account for a large part of the changes in lipid composition observed during the fermentation. The pH was also important, a decrease in pH resulting in a decrease in the U/S ratio and in an increase in cyclopropane fatty acids. The effect of increasing temperature was mainly to increase fatty acid chain lengths.