earticle

영어

The application of the cellulase gene (celA) as a selection marker of food-grade integration system wasinvestigated in Lactobacillus (Lb.) casei, Lactococcus lactis, and Leuconostoc (Leu.) mesenteroides. The 6.0-kb vector pOC13containing celA from Clostridium thermocellum with an integrase gene and a phage attachment site originating frombacteriophage A2 was used for site-specific recombination into chromosomal DNA of lactic acid bacteria (LAB). pOC13 wasalso equipped with a broad host range plus replication origin from the lactococcal plasmid pWV01, and a controllablepromoter of nisA (PnisA) for the production of foreign proteins. pOC13 was integrated successfully into Lb. casei EM116, andpOC13 integrants were easily detectable by the formation of halo zone on plates containing cellulose. Recombinant Lb. caseiEM116::pOC13 maintained these traits in the absence of selection pressure during 100 generations. pOC13 was integrated intothe chromosome of L. lactis and Leu. mesenteroides, and celA acted as an efficient selection marker. These results show thatcelA can be used as a food-grade selection marker, and that the new integrative vector could be used for the production offoreign proteins in LAB.