Abstract:The food-grade secretion expression vector of β-glucosidase from Aspergillus aculeatus was constructed and expressed in Lactococcus lactis MG1363. Secretion signal peptide Usp45 from the L. lactis MG1363 genome, Nisin resistance genes NisI from plasmid pLEB590 and Abgl from plasmid pPIC9k-Abgl were amplified by PCR and ligated to construct the Usp45-Abgl-NisI fragment. The fragment was subcloned into plasmid pMD19 and then transformed into E.coli DH5α by CaCl2 method. It was identified by sequencing and inserted into the E.coli-Lactic acid bacteria shutter vector pMG36e. The recombinant strain E.coli XL1-Blue/pMG36e-Usp45-Abgl-NisI was obtained by transformation. Food-grade secretion expression vector pMG36N-Usp45-Abgl-NisI, in which erythromycin resistance gene of plasmid pMG36e-Usp45-Abgl-NisI was knocked out by PCR method, was constructed and then electrotransformed into L. lactis MG1363. β-Glucosidase produced by E.coli XL1-Blue was active on the chromogenic substrate aesculin. L.lactis MG1363/pMG36N-Usp45-Abgl-NisI could grow on the plates containing 20IU/mL Nisin. β-Glucosidase expressed in L.lactis MG1363 was verified by RT-PCR.
