Our objective is to solve the lactose malabsorption and intolerance of human beings by combining micro-ecology path with genetic engineering technique. Plasmid pMG36e was used to clone and express a β-galactosidase g...Our objective is to solve the lactose malabsorption and intolerance of human beings by combining micro-ecology path with genetic engineering technique. Plasmid pMG36e was used to clone and express a β-galactosidase gene from L. delbrueckü bulgaricus strain 1.1480 in the Lactococcus lactis subsp. cremoris MG1363 and Lactococcus lactis subsp. lactis IL1403. The recombinant plasmid was preserved and proliferated in Escherichia coli ( E. coli) JM109, and transformed into MG1363 and IL1403 by electroporation. The protein expression was studied. ( 1 ) The bifidobacterium culture medium ( BBL) was suitable for the growth of the strain 1.1480. (2) With 13 amino acids at the N-terminus from the vector, β-gal- actosidase fusion protein (which retained the enzyme activity) could be successfully expressed in E. coli JM109, MG1363 and IL1403, but the expression quantity was larger in the former than in the latter two. (3) The SD sequence designed could be successfully recognized by both the E. coli and the Lactococcus lactis, but the expression level of the non-fusion β-galac- tosidase protein was lower than that of the fusion protein in the same host. The β-galactosidase genetically engineered E. coli JM109 is a useful tool to produce this enzyme in vitro . The signal peptide of the usp45 protein from the Lactococcus lac- tis can be added before the promoter sequence to promote β-galactosidase secretion from Lactococcus lactis . The potential ap- plication of the β-galactosidase genetically engineered MG1363 and IL1403 to cure the lactose malabsorption and lactose in- tolerance in both health food and medicine is promising.展开更多
文摘Our objective is to solve the lactose malabsorption and intolerance of human beings by combining micro-ecology path with genetic engineering technique. Plasmid pMG36e was used to clone and express a β-galactosidase gene from L. delbrueckü bulgaricus strain 1.1480 in the Lactococcus lactis subsp. cremoris MG1363 and Lactococcus lactis subsp. lactis IL1403. The recombinant plasmid was preserved and proliferated in Escherichia coli ( E. coli) JM109, and transformed into MG1363 and IL1403 by electroporation. The protein expression was studied. ( 1 ) The bifidobacterium culture medium ( BBL) was suitable for the growth of the strain 1.1480. (2) With 13 amino acids at the N-terminus from the vector, β-gal- actosidase fusion protein (which retained the enzyme activity) could be successfully expressed in E. coli JM109, MG1363 and IL1403, but the expression quantity was larger in the former than in the latter two. (3) The SD sequence designed could be successfully recognized by both the E. coli and the Lactococcus lactis, but the expression level of the non-fusion β-galac- tosidase protein was lower than that of the fusion protein in the same host. The β-galactosidase genetically engineered E. coli JM109 is a useful tool to produce this enzyme in vitro . The signal peptide of the usp45 protein from the Lactococcus lac- tis can be added before the promoter sequence to promote β-galactosidase secretion from Lactococcus lactis . The potential ap- plication of the β-galactosidase genetically engineered MG1363 and IL1403 to cure the lactose malabsorption and lactose in- tolerance in both health food and medicine is promising.
