Expression, Purification and Enzymatic Properties Study of the Bile Salt Hydrolase from Bifidobacterium in Escherichia coli

Abstract:

The bile salt hydrolase gene from Bifidobacteriuminfantis KL412 was expressed using Escherichia coli to increase the expression level and study the enzymatic properties of the recombinant bile salt hydrolase. The bile salt hydrolase gene was first amplified by PCR and cloned into the expression vector pET-22b（+）. The recombinant plasmid pET-22b（+）-bsh was the transformed to E. coli BL21 （DE3）. The optimized activity to glycodeoxycholic acid（GDCA） and taurine sodium deoxycholate（TDCA） of the recombinant bile salt hydrolase could reach to 135.2 U/mL and 121.3 U/mL at 20 ℃ for 32 h with 1 mM IPTG. The molecular weight of bile salt hydrolase was 35.0×103 analyzed by SDS-PAGE after purification through Ni-chelating affinity chromatography. The investigation on enzymatic properties showed that the recombinant bile salt hydrolase had a preference to glycine bile salts and a highest activity was achieved at 220.1 U/mg to sodium glycocholate（GCA）. This study provided a reference for the expression of bile salt hydrolase from different sources in genetically engineered bacteria and the further study of the structure and catalytic mechanism of bile salt hydrolase.