Optimization Strategy of Expression Vectors and Regulatory Elements for Enhanced Protein Production in Bacillus subtilis

As a non-pathogenic, Gram-positive strain, Bacillus subtilis is well-known for its efficient protein secretion mechanism and versatile microbial cell factory. However, the present B. subtilis expression vectors have drawbacks that prevent their industrial use, such as poor stability, low copy number, and low expression efficiency. In recent years, systematic optimization of expression vectors and elements has emerged as a key strategy for enhancing protein production efficiency. Among these efforts, constructing high-copy, stable vector backbones serves as the foundation for improving heterologous protein expression. Further optimization of critical regulatory elements—including regulatory genes, promoters, ribosome binding sites, signal peptides, and terminators—can significantly increase protein yield and process controllability. This review summarizes recent advances in B. subtilis expression systems, focusing on vector design and coordinated optimization of regulatory elements. Additionally, it discusses strategies for constructing efficient and controllable expression vectors, offering theoretical insights and technical guidance for future industrial applications.