A Protocol to Enhance Soluble Protein Expression in the Cytoplasm of Bacillus subtilis

Bacillus subtilis is a generally regarded as safe (GRAS) microorganism, which has been used for industrial production of recombinant enzymes. Many inducible and inducer-free expression vectors have been developed for intracellular production; some of those demonstrated the capability for protein expression up to 42% of total cellular proteins. In this chapter, we introduce the method to enhance the expression of soluble protein in B. subtilis. It includes the construction of vectors, the transformation of a plasmid into B. subtilis, and checking the expression of the protein.