Recombinant EXLX1 from <i>Bacillus subtilis</i> for enhancing enzymatic hydrolysis of corn stover with low cellulase loadings

Abstract

BsEXLX1 protein from Bacillus subtilis has been proposed to have a structure that is similar to plant expansin. In this study, the recombinant BsEXLX1 protein was successfully expressed and purified in Escherichia coli BL21 (DE3). When the purified BsEXLX1 which contained the thioredoxin (Trx) protein was incubated with low-dose cellulases either simultaneously or sequentially, it showed a significant synergistic activity in corn stover hydrolysis. Furthermore, an even greater increase in the synergistic activity was obtained when cellulose was pretreated with BsEXLX1 followed by cellulase hydrolysis, and the synergistic activity was found as high as 1.5-fold greater than that when cellulose was treated simultaneously with the same concentrations of BsEXLX1 and cellulases. These results provided a feasible way for the potential application of BsEXLX1 in the efficient saccharification of cellulose materials for bioethanol production.

Key word: Bacillus subtilis, BsEXLX1, cellulase, cellulose hydrolysis, bioethanol