[Influence of acid adaptation on membrane-fatty acid profile and expression of membrane proteins in Lactococcus lactis].
OBJECTIVE
Lactococcus lactis with high acid adaptive capacity was screened, and the influence of acid adaptation 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 membrane 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 saturated fatty acids from 69.23% to 57.07%, and a new long-chained, mono-unsaturated fatty acid Cs9:1-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.


CONCLUSIONS
These results showed that change in the membrane fatty acid profile by acid adaptation in Lactococcus lactis
Liu
Huailong
H
Key Laboratory of Dairy Science, Ministry of Education, and Food Science & Technology College, Northeast Agricultural University, Harbin, China.
Meng
Xiangchen
X
D000222:Adaptation, Physiological / Q000187:drug effects* / Q000502:physiology; D005227:Fatty Acids / Q000494:pharmacology*; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D015870:Gene Expression / Q000502:physiology; D013294:Lactococcus lactis / Q000187:drug effects* / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*
D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated; D008565:Membrane Proteins