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

目的]筛选具有较强酸适应能力的菌株,研究酸适应对其膜脂肪酸组成和膜蛋白表达的影响.方法]从20株菌中筛选出一株具有较强酸适应能力的乳酸乳球菌KLDS4.0312,以GC-MS法测定该菌酸适应前后膜脂肪酸组成变化;对酸适应前后该菌膜蛋白的差异表达进行双向电泳分析.结果]酸适应后,该菌膜不饱和脂肪酸含量从30.77%上升到42.93%,饱和脂肪酸含量从69.23%下降到57.07%,且有一种新的长链单不饱和脂肪酸C<,19:1>-n6被诱导产生.酸适应过程中至少有65个蛋白质点表达出现显著差异,其中上调的蛋白质点有43个,减弱表达的蛋白质点有22个.而添加氯霉素后,菌株的酸适应能力消除,可能与氯霉素抑制新蛋白的合成有关.结论]说明细胞膜脂肪酸组成的适应性改变和应激蛋白的诱导产生是该菌主要的酸适应机制.

Influence of Acid Adaptation on Membrane Fatty Acid Profile and Expression of Membrane proteins in Lactococcus lactis

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.