Payne J, MacCormick C A, Griffin H G, Gasson M J
Institute of Food Research, Norwich Research Park, Colney, UK.
FEMS Microbiol Lett. 1996 Feb 1;136(1):19-24. doi: 10.1016/0378-1097(95)00474-2.
Lactococcus lactis MG5267 is a plasmid-free strain in which the lactose operon is integrated in the bacterial chromosome. The chromosomal lacG gene which encodes phospho-beta-galactosidase was inactivated by a double cross-over integration event. Unexpectedly, the resultant mutant was shown to retain a Lac-positive phenotype. The lysin gene from Listeria monocytogenes bacteriophage LM-4 was subsequently integrated into the chromosome of this strain such that expression of the heterologous gene was mediated by the lactose operon promoter. Expression of the lysin gene was shown to be regulated by growth on lactose. This represents an important strategy for the controlled and stabilised expression of biotechnologically useful genes in L. lactis.
乳酸乳球菌MG5267是一种无质粒菌株，其中乳糖操纵子整合在细菌染色体中。编码磷酸β-半乳糖苷酶的染色体lacG基因通过双交换整合事件失活。出乎意料的是，所得突变体显示保留Lac阳性表型。随后将来自单核细胞增生李斯特氏菌噬菌体LM-4的溶素基因整合到该菌株的染色体中，使得异源基因的表达由乳糖操纵子启动子介导。溶素基因的表达显示受乳糖生长的调节。这代表了在乳酸乳球菌中控制和稳定表达生物技术有用基因的重要策略。
