Abstract: The protein BSH, from Lactobacillu plantarum Y1, can form inclusion body when expressed in E. coli. The fusion tag IF2 can improve its solubility on the basis of our previous studies. In the present study, five fusion tags such as SUMO, GST, NusA, MBP and IF2 were used to improve the solubility of BSH. The results showed that an obvious protein band of MBP-BSH in the culture supernatant of recombinant E. coli Rosetta (DE3) (pLS932-BSH)was observed during the examination of SDS-PAGE. However, after induction, its solubility was greatly improved. Meanwhile, Ni-NTA resin exhibited better purification efficiency for MBP-BSH protein than Amylose resin. In addition, His-Tag linked at the C-terminal was favorable for the binding of nickel ions and as a result, MBP-BSH containing less impurities was obtained in a higher yield. The enzymatic activity of purified BSH was 2.4282 U/mg (115.14 AU/mg) as determined by ninhydrin color reaction.

Key words: fusion protein MBP-BSH, expression and purification, functional characterization, bile salt hydrolase