Glycine and Triton X-100 enhanced secretion of recombinant α-CGTase mediated by OmpA signal peptide in Escherichia coli

OmpA signal peptide mediated cgt gene from Paenibacillus macerans JFB05-01 was cloned and expressed in E. coli BL21 (DE3). The effects of glycine and Triton X-100 on extracellular production of α-cyclodextrin glycosyltransferase (α-CGTase) were investigated. When supplemented with Gly or Triton X-100 to the culture media individually, the secreted extracellular enzyme reached 32 or 33 U/mL at 48 h of cultivation, respectively. When supplemented with Gly and Triton X-100 together, the extracellular α-CGTase activity reached 48 U/mL after 48 h cultivation, which was 20-fold of the control group without any additives. Analysis of membrane permeability demonstrated that addition of glycine and Triton X-100 enhanced the permeability of both outer and inner membrane. The potential mechanism of the enhanced protein secretion was discussed.