Abstract:Bacillus has good protein expression and secretion ability, and is widely used in the production of industrial enzymes. There are still many bottlenecks to achieve protein secretory expression with a generally high efficiency, although it is an ideal industrial host strain. In this review, the secretion pathway of protein in Bacillus is briefly described, and we summarize the strategies of host strain optimization for recombinant protein production from five different aspects, including promoter, signal peptide, secretion pathway, host strain and culture conditions, which has certain reference value for the efficient production of industrial enzymes in Bacillus. The research direction of optimizing secretory expression of Bacillus in the future is prospected. The development of various new biotechnology will certainly promote the further application of Bacillus in secretory expression.