Enhanced expression of an endoglucanase in Bacillus subtilis by using the sucrose-inducible sacB promoter and improved properties of the recombinant enzyme

An endoglucanase from Bacillus akibai I-1 was successfully overexpressed in Bacillus subtilis 168 and the expression level of the recombinant enzyme was greatly enhanced by using the sucrose-inducible sacB promoter. The endoglucanase activity in the culture supernatant of recombinant B. subtilis by using itself promoter (HpaII) in plasmid pMA5 was 3 U/ml. Interestingly, with the addition of sacB promoter at downstream from the HpaII promoter or the replacement of HpaII promoter by the sacB promoter, the endoglucanase activities reached 62 and 60 U/ml, respectively, under the optimal culture conditions. These results demonstrated that the sacB promoter might be more efficient for the expression of the endoglucanase than the HpaII promoter. More interestingly, the purified native enzyme had broad pH stability, good thermostability and resistibility to various metal ions and chelating agents examined, while the recombinant enzyme had improved resistibility to SDS, which was stable in 0.2% (w/v) laundry detergent and thus showed great potential in detergents industry.

► We find a novel bacterial endoglucanase which has excellent properties.
► The endoglucanase is successfully overexpressed in Bacillus subtilis.
► The expression level is greatly enhanced by using the sucrose-inducible sacB promoter.
► We find the recombinant enzyme has improved resistibility to SDS.
► The recombinant enzyme is stable in laundry detergent and shows great potential in detergents industry.