NATURE OF THE LIPIDS OF SOME LACTIC ACID BACTERIA.

Ikawa, Miyoshi (University of California, Berkeley). Nature of the lipids of some lactic acid bacteria. J. Bacteriol. 85:772-781. 1963.-Lactobacillus casei, L. plantarum, Leuconostoc mesenteroides, Pediococcus cerevisiae, and Streptococcus faecalis were grown on a lipid-free medium, and the amounts of acetone-soluble lipids, acetone-insoluble phospholipids, and unextracted or bound lipid in the cells were estimated. Neutral glycerides appeared to be absent, or present only in traces, in L. casei and S. faecalis. L. plantarum, L. mesenteroides, and P. cerevisiae, in addition to containing glycerides, appeared to contain glycolipids of glucose and galactose. Glycerol was present in the phospholipid fraction of all the organisms, and, in addition, galactose was present in L. mesenteroides. Paper chromatography of hydrolysates of the phospholipid fractions showed the absence of the usual phospholipid nitrogen bases, serine, ethanolamine, and choline, in these organisms. Microbiological assays of lyophilized unextracted cells for myo-inositol and choline also showed that lipids containing these components occurred in very small amounts at most. The principal ninhydrin-reacting substance in the phospholipid fraction of L. casei, L. plantarum, P. cerevisiae, and S. faecalis was lysine, which seemed to be exclusively of the l configuration. The principal ninhydrin-reacting substance in the L. mesenteroides phospholipid fraction was d-alanine. These amino acids appeared to be bound in components of the phospholipid fraction and not free.