Piard J C, Delorme C, Novel M, Desmazeaud M, Novel G
INRA, Station de Recherches Laitières, Jouy-en-Josas, France.
FEMS Microbiol Lett. 1993 Sep 15;112(3):313-8. doi: 10.1111/j.1574-6968.1993.tb06468.x.
The lacticin 481-producer (Lct+), L. lactis subsp. lactis (L. lactis) CNRZ 481 harbours 5 plasmids of 6.5, 7.5, 20, 37 and 69 kb. Novobiocin treatment of L. lactis 481 led to the appearance of lacticin 481 deficient variants which had all lost the 69 kb plasmid. Conjugal transfer of the lacticin 481 structural gene (lct) into the plasmid free strain L. lactis IL1441 yielded Lct+ transconjugants at a 10(-4) frequency, which carried a plasmid with an apparent size of 120-130 kb. Southern hybridization analyses showed that the lct gene was located on the 69 kb plasmid in L. lactis 481 and on the 120-130 kb plasmid in the transconjugants. The lct gene was in higher copy number in transconjugants than in the parental strain resulting in two-fold higher lacticin 481 production in the former strain.
产乳酸链球菌素481（Lct+）的乳酸乳球菌乳酸亚种（乳酸乳球菌）CNRZ 481含有5个质粒，大小分别为6.5、7.5、20、37和69 kb。用新生霉素处理乳酸乳球菌481，导致出现乳酸链球菌素481缺陷型变体，这些变体均丢失了69 kb的质粒。将乳酸链球菌素481结构基因（lct）接合转移至无质粒菌株乳酸乳球菌IL1441，以10^(-4)的频率产生了Lct+接合子，其携带一个表观大小为120 - 130 kb的质粒。Southern杂交分析表明，lct基因在乳酸乳球菌481中位于69 kb的质粒上，而在接合子中位于120 - 130 kb的质粒上。lct基因在接合子中的拷贝数高于亲代菌株，导致前者菌株中乳酸链球菌素481的产量高出两倍。
