Expression of β-(1,3-1,4)-glucanase gene of Orpinomyces sp. GMLF18 in Escherichia coli EC1000 and Lactococcus lactis subsp. cremoris MG1363

摘要

A gene encoding β-(1,3-1,4)-glucanase (licA) was amplif ed from Orpinomyces sp. GMLF18 and expressed in Escherichia coli. The DNA sequence of licA showed that the gene was 707 bp and encoded a protein with a molecular mass of 26 kDa that belongs to family glycosyl hydrolase 16. The main LicA activity was observed to be cell-associated for the licA containing transformant E. coli, and the enzyme expressed in E. coli showed the highest activity at pH 5.0-6.0 and at temperatures of 40-50 °C. The enzyme was found to be stable at 40 °C; however, 12% of LicA activity was lost at 50 °C in 20 min. The licA was then introduced into the facultative anaerobic bacterium Lactococcus lactis subsp. cremoris MG1363 by a stable recombinant plasmid, pIL253. Although the enzymatic activity was lower than that in E. coli, the gene encoding the fungal originated lichenase was successfully expressed in L. lactis.