Enhancing secretion of polyethylene terephthalate hydrolase PETase inBacillus subtilisWB600 mediated by the SPamysignal 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 inBacillus subtilis. In this study, the coding gene of PETase, which was isolated from theIdeonella sakaiensis, was synthesized and expressed inB. subtilis. Then, we evaluated the ability of fiveBacillussignal peptides to enhance PETase secretion byB. subtilis. The results indicated that the SPamy-induced secretion of PETase was the highest, and its activity againstp-Nitrophenyl palmitate was about fourfold that of the natural signal peptide SPPETase. 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 byB. subtilis. Our findings will facilitate biodegradation of PET plastic.