Enhancing secretion of polyethylene terephthalate hydrolase PETase in Bacillus subtilis WB600 mediated by the SP amy signal peptide

The polyethylene terephthalate hydrolase (PETase) has been proved to have a high activity to degrade polyethylene terephthalate (PET), but few studies have been carried on its secretion in Bacillus subtilis. In this study, the coding gene of PETase, which was isolated from the Ideonella sakaiensis, was synthesized and expressed in B. subtilis. Then, we evaluated the ability of five Bacillus signal peptides to enhance PETase secretion by B. subtilis. The results indicated that the SP_amy -induced secretion of PETase was the highest, and its activity against p-Nitrophenyl palmitate was about fourfold that of the natural signal peptide SP_PETase . The weak promoter P43 provided sufficient time for translation and folding of PETase, resulting in increased extracellular expression. Use of P43 and SP_amy in combination yielded the greatest bis-(2-hydroxyethyl) terephthalate degradation and PET-film etching activity due to maximized secretion of PETase by B. subtilis. Our findings will facilitate biodegradation of PET plastic. SIGNIFICANCE AND IMPACT OF THE STUDY: High-level expression of polyethylene terephthalate hydrolase (PETase) facilitates biodegradation of PET. In this study, the expression elements, signal peptide and promoter, in the secretory expression system, were optimizing for maximizing secreted expression of PETase in Bacillus subtilis. The constructed strains yielded the greatest bis-(2-hydroxyethyl) terephthalate degradation and PET-film etching activities.