Reasons for the differences in biotransformation of conjugated linoleic acid by Lactobacillus plantarum

摘要

Conjugated linoleic acid (CLA) has attracted a greatdeal of attention for its functions in weight loss, regulationof metabolism, and antioxidant capabilities. Manymicroorganisms, including rumen bacteria, propionicacid bacilli, and Lactobacillus, have CLA biotransformationability. The CLA production capability of differentspecies is different, as are those different strains of thesame species. However, the reasons for this discrepancyremain unclear. In this study, 14 strains of Lactobacillusplantarum were found, through gas chromatographymassspectrometry analysis, to be capable of convertinglinoleic acid to CLA. The transcriptional levelsof CLA-related genes in the high- (AR195, WCFS1,and AR488) and low-yield strains (AR176, AR269,and AR611) were analyzed using real-time quantitativePCR. The transcriptional levels of cla-hy, cla-dh,and cla-dc in AR195 were the lowest in the exponentialphase, but it had the highest CLA yield. Correlationanalysis showed no correlation between CLA yield andthe transcription level of these genes in the exponentialphase. The results showed that a high transcriptionallevel in the exponential phase of cla-hy, cla-dh, andcla-dc did not necessarily lead to high CLA production.Investigation of the transcription level in differentgrowth phases showed that the CLA biotransformationabilities of Lactobacillus plantarum strains significantlydepended on the transcriptional maintenance of cla-hy,cla-dh, and cla-dc. We observed a correlation betweenCLA production and increased levels of cla-hy transcription,but a prerequisite is needed: the transcriptionof cla-dh and cla-dc should be upregulated and maintaineda high transcriptional level during the platformperiod. This study provides a new strategy for screeninghigh CLA-producing strains. It also lays a theoreticalfoundation for regulating CLA biotransformation andincreasing the yield of CLA.