Using inexpensive substrate to achieve high-level lipase A secretion by Bacillus subtilis through signal peptide and promoter screening

Abstract

Lipase A exhibits great commercial value due to its applications in the food and paper industry, pharmaceutical chemistry and household chemicals. In this study, we first conducted a comparison of different signal peptides and promoters for the construction of the productive lipase A strain. The maximum extracellular lipase activity was identified as 64.9 U/mL after 12-h fermentation at 37 °C by B. subtilis L25 in which the lipase gene was led by SPlipA and controlled by P43-Phag. Another aim was to determine whether supplementing a culture medium with a combination of glycerol and Streptomyces sp. SCUT-3 digested chicken feather hydrolysates was beneficial to lipase production. Systematic optimization experiments were designed and carried out. Finally, a satisfactory lipase level of 1164.9 U/mL was accomplished in Terrific-Broth medium at a C/N ratio of 0.5 (v/v). This work demonstrates the feasibility of B. subtilis L25 for lipase A industrial production using glycerol and microbes treated chicken feather hydrolysates as inexpensive carbon and nitrogen source.