ABSTRACT
To construct a secretory-expression vector of antimicrobial peptide Bactenecin 7(Bac7),and identify the secretory-expression product in L.lactis MG1363 and its bioactivity.The splicing primers of regulation elements and Bac7 gene,which designed according to codon usage preferences of L.lactis MG1363,were chemically synthesized,and the overlap-extension PCR method was used to splice the full length of Bac7 gene.Then the Bac7 gene was linked to expression vector pMG36e to construct pMG36e/Bac7 vector,and pMG36e/Bac7 was transformed into L.lactis MG1363 by electrophoration.RT-PCR and Western blot assays were applied to investigate the expression of the Bac7 gene in L.lactis,and bioactivity of Bac7 in culture supernatant of L.lactis was tested with plate-diffusion method.The results showed that the Bac7 gene and its regulation elements was amplified and cloned in the vector pMG36e successfully,The secretory-expressed Bac7 in L.lactis MG1363 harboring pMG36e/Bac7 was identified by Western blot,and it had high bacteriostatic activity against E.coli.These results indicate that the recombinant L.lactis MG1363 could express bioactive Bac7,which lays a foundation for further study of oral administration of a Bac7-secreting L.lactis to treat intestinal bacteria infection.