Influence of Acid Adaptation on Membrane Fatty Acid Profile and Expression of Membrane proteins in Lactococcus lactis
酸适应对一株乳酸乳球菌膜脂肪酸组成和膜蛋白表达的影响

Abstract: Objective] Lactococcus lactis with high acid adaptive capacity was screened, and the influence of acid adap-tation on membrane fatty acid profile and expression of membrane proteins were studied. Methods] Lactococcus lactis KLDS4.0312 with high acid adaptive capacity was screened from 12 lactic acid bacteria and 8 Bifidobacterium. The change of the fatty acid profile in cell membrane of this strain was analyzed by gas chromatography-mass spectrometry, and two dimensional polyacrylamide gel electrophoresis method was used to analyze the differential expression of mem-brane proteins during the acid adaptation. Results] After acid adaptation, Lactococcus lactis KLDS4.0312 increased the proportion of unsaturated fatty acids from 30.77% to 42.93% in its membrane lipids with a concomitant decrease in satu-rated fatty acids from 69.23% to 57.07%, and a new long-chained, mono-unsaturated fatty acid C19:1-n6 was induced. Compared with the non-adapted sample, there were at least 65 distinct protein points in the adapted sample, where 43 proteins were up-regulated and 22 proteins were down-regulated. But the acid adaptive capacity of Lactococcus lactis KLDS4.0312 was eliminated by adding chloramphenicol which can restrain the synthesis of new proteins. Conclusion] These results showed that change in the membrane fatty acid profile by acid adaptation in Lactococcus lactis KLDS4.0312.