植物乳杆菌生物转化共轭亚油酸的分子机理及调控机制

Conjugated linoleic acid (CLA) is a generic term used to describe a group of linoleic acid isomers with conjugated double bonds. CLA can be produced with chemical method, but the synthesized product is complex and often a mixture of CLA isomers. Biological method for CLA production has attracted much attention as specific pure CLA isomer can be synthesized. Among microbial CLA producers, lactic acid bacteria (LAB) can produce cis-9, trans-11-CLA and trans-9, trans-11-CLA, which have better anti-cancer and immunity-stimulating activities compared to the other isomers. A number of lactic acid bacteria has been reported to produce cis-9, trans-11-CLA and trans-9, trans-11-CLA, however, the exact enzyme(s) responsible for their synthesis is(are) still unclear. We have isolated a high CLA producing LAB, ZS2058, and generated genomics and transcriptomics data. In this proposal we will study the CLA metabolic pathway in ZS2058 using a combination of bioinformatics, molecular biology, enzyme activity assay and metabolites analysis approaches. Information obtained would be helpful for dairy fermentation of CLA, and genetic engineering of LAB for CLA industrial production in the future.

作为新型保健功能脂质的共轭亚油酸（CLA）是一类从亚油酸衍生出的共轭双烯酸异构体的总称。传统化学法获得的CLA产物是多种异构体混合物，而乳酸菌能产在抗癌、提高免疫力方面功能相比其他异构体更强的cis-9, trans-11-CLA及trans-9, trans-11-CLA，因此利用微生物选择性合成CLA活性异构体成为当前研究热点。目前已报道多种产功能性CLA的乳酸菌，但乳酸菌中与CLA生物转化相关的是多酶复合体系，其调控机制目前尚不清楚。本项目拟在组学研究基础上，以课题组筛获的一株高产cis-9, trans-11-CLA的植物乳杆菌为研究对象，在基因转录、功能和代谢物积累水平解释该菌生物转化CLA相关基因的调控规律，全面解析植物乳杆菌生物转化CLA通路及其调控机制，为将其用于富含功能性CLA发酵乳制品生产提供指导，也为将乳酸菌遗传改良使其适用于工业化生产CLA奠定重要的物质与理论基础。

植物乳杆菌能产共轭亚油酸（CLA）活性异构体，但其产共轭亚油酸的生物转化机制和调控机理还不明确。本项目在组学研究基础上，以课题组筛获的一株高产cis-9, trans-11-CLA的植物乳杆菌为研究对象，确证了植物乳杆菌ZS2058中生物转化CLA的亚油酸异构酶系，亚油酸经亚油酸水合酶、短链氧化/还原酶、乙酰乙酸脱羧酶三酶催化生物转化为CLA。项目进一步在基因转录、功能和代谢物积累水平阐明和验证了该菌生物转化CLA相关基因的调控规律，最后通过动物实验证明了植物乳杆菌ZS2058可通过代谢LA生成CLA改善小鼠结肠炎症状。这为将植物乳杆菌用于富含功能性CLA发酵乳制品生产提供了指导，也为将乳酸菌遗传改良使其适用于工业化生产CLA奠定了重要的物质与理论基础。