Overexpression of cyclodextrin glycosyltransferase gene from Brevibacillus brevis in Escherichia coli by control of temperature and mannitol concentration

Abstract

Expression of Brevibacillus brevis CD 162 cyclodextrin glycosyltransferase (CGTase) gene using pET22b(+) vector in Escherichia coli BL21 (DE3) resulted in the formation of inactive inclusion bodies under the usual induction conditions. However, by lowering the induction temperature to 30°C and/or adding 0.5 M mannitol as an osmolyte, the formation of insoluble aggregates was prevented and about a 34-fold increase (8.51 U ml-1) in biologically active soluble form was achieved after 6 h induction. The active CGTase enzyme was estimated to comprise as much as 24% of the total soluble proteins. In addition, other polyols such as glycerol, erythritol, xylitol, sorbitol, and arabitol showed similar effects with mannitol on the production of active CGTase enzyme.