Cloning of Bile Salt Hydrolase Gene and Its Expression in Lactic Acid Bacteria

According to the sequence of the bile salt hydrolase （BSH） gene of Bifidobacterium and the restriction enzyme cutting sites of expression vector pNZ8148, primers were designed and the bile salt hydrolase （BSH） gene was gotten from Bacillus bifidus ATCC 29521 by PCR. BSH gene was inserted into lactic acid bacteria expression vector pNZ8148 to construct the recombinant pNZ8148-BSH. The recombinant pNZ8148-BSH was transferred into lactic acid bacteria NZ9000 with electrotransformation method. And the recombinant which could express BSH protein was obtained. It was identified by SDS-PAGE electrophoresis and activity verification. The result could provide a rationale reference for expressing BSH in lactic acid bacteria.

Cloning and Expression of Bile Salt Hydrolase Gene from Lactobacillus plantarum M1-UVS29

We cloned and expressed bile salt hydrolase gene ofLactobacillus plantarum M1-UVS29 in Lactococcus lactis NZ9000 successfully. Gene-specific primers for amplification of L. plantarum bsh were designed by using sequence which availabled from GenBank. The production of PCR amplicon was confirmed by sequencing and cloned into pMD18-T vector, and then recombined into expression vector pNZ8148 and yielding vector pNZ8148-BSH, pNZ8148-BSH was transferred into Lactococcus lactis NZ9000. Sequencing indicated that the cloned bsh fragment contained 995 nucleotides, and shared 99.3% sequence homology with bsh gene from L. plantarum MBUL10. Cloned bsh fragment was successfully transduced into NICE expression system and confirmed by PCR and restriction digest. Recombinant BSH protein was analyzed by SDS-PAGE. The molecular weight of BSH protein was approximately 37 ku. Activity of the expressed protein was 0.77 μmol· min^-1. The successfully expressed proteins by genetic engineering technology made the function of lactic acid bacteria be abundant and laid the foundation for further researches into cholesterol-lowering lactic acid bacterium food and probiotics.

Role of gut microbiota in the development of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease(NAFLD)is a chronic liver disease characterized by hepatic steatosis in the absence of other causes,such as chronic alcohol consumption,that cause secondary hepatic fat accumulation.NAFLD has become the most common liver disease worldwide over the past two decades,and the prevalence of NAFLD is 20e30%in Western countries.However,the mechanism of NAFLD re-mains unclear.The gut microbiota plays an important role in the metabolism of the host;in fact,it has been implicated in inflammatory diseases,metabolic syndrome and cardiovascular disease.Accumu-lating evidence has indicated that gut microbiota component changes are linked to human obesity,in-sulin resistance(IR),type 2 diabetes and NAFLD.Here,we provide insight into the role of gut microbiota,especially bile salt hydrolase(BSH)in modulating the bile acid pool and farnesoid X receptor(FXR),which promotes the synthesis of ceramide and contributes to the development of NAFLD.