RESUMO
Objective To construct a prokaryotic expression vector in BL21 to secretorily expressα-Cyclodextrin Glycosyltransferase(α-CGTase). Methods α-CGT gene was amplified from Bacillus macerens genome by PCR.pET26b and α-CGT gene were connected after digested with Nco I, Xho I respectivly, and then transformed into Escherichia coli BL21 strain.α-CGTase was expressed in fermentation culture medium and AA-2G was prepared by using α-CGTase, VC and starch.Results α-CGTase was expressed secretorily and the enzyme activity was up to 120 U/mL.AA-2G was prepared by the biotransformation of VC and starch using α-CGTase which proved to be correct by HPLC.Conclusion AA-2G was prepared by using self-madeα-CGTase, after optimized the preparation conditions the yield of AA-2G was 17.46 g/L, and the conversion rate reached 58.2%(mg/mg).