Promoter and signal peptide optimization increases the secretory expression of glutaminase in Bacillus subtilis

Abstract:

[Background] Glutaminase is an enzyme which can catalyzes the hydrolysis of l-glutamine to l-glutamic acid and ammonia, and it has been well used in the food and medicine fields. [Objective] To study the influences of different promoters and signal peptides on the secretory expression of glutaminase and construct recombinant Bacillus subtilis strains with efficient secretory expression of glutaminase to improve the production of glutaminase. [Methods] B. subtilis SCK6 was selected as the host, and the glutaminase expression vectors and recombinant strains with different promoters and signal peptides were constructed. The effects of different gene elements on the expression and secretion of glutaminase were studied, and the optimal promoter and signal peptide were selected and combined to construct an efficient and robust glutaminase-producing strain. [Results] A recombinant strain with efficient secretory expression of glutaminase was constructed. With P_HpaII-P_aprE as the promoter and YndA as the signal peptide, the strain showed the extracellular glutaminase activity reaching 6.7 U/mL in shake flask fermentation. [Conclusion] By screening and combining the promoter and signal peptide, we constructed a recombinant strain with robust production of glutaminase, providing an effective method for the efficient secretory expression of enzymes.