Harmon K S, McKay L L
Appl Environ Microbiol. 1987 May;53(5):1171-4. doi: 10.1128/aem.53.5.1171-1174.1987.
The 131.1-kilobase (kb) bacteriocin production (Bac) plasmid pNP2 and the 63.6-kb lactose metabolism (Lac) plasmid pCS26, from Streptococcus lactis subsp. diacetylactis WM4, as well as pWN8, a 116.7-kb recombinant plasmid from a Lac+ transconjugant, were analyzed with restriction enzymes to determine the origin of pWN8. Plasmid pWN8 conferred a Lac+ Bac- phenotype, contained DNA derived from pCS26 and pNP2, and, like pNP2, exhibited self-transmissibility (Tra+). In cloning attempts, Bac+ transformant S. lactis KSH1 was isolated. The recombinant plasmid, pKSH1, contained three BclI fragments from pNP2. Bac- transformants which individually contained each of the three fragments were also identified. Comparison of restriction maps of pKSH1 and pNP2 revealed an 18.4-kb region common to both plasmids, involving two of the three BclI fragments. S. lactis KSH1 also exhibited greater inhibitory activity against the indicator strain S. diacetylactis 18-16 than did a strain containing the 131.1-kb Bac plasmid.
对来自乳酸乳球菌亚种双乙酰乳酸亚种WM4的131.1千碱基（kb）的细菌素产生（Bac）质粒pNP2、63.6 kb的乳糖代谢（Lac）质粒pCS26以及来自Lac⁺转接合子的116.7 kb重组质粒pWN8进行了限制性酶切分析，以确定pWN8的来源。质粒pWN8赋予Lac⁺Bac⁻表型，含有源自pCS26和pNP2的DNA，并且与pNP2一样，表现出自我传递性（Tra⁺）。在克隆尝试中，分离出了Bac⁺转化体乳酸乳球菌KSH1。重组质粒pKSH1包含来自pNP2的三个BclI片段。还鉴定出了分别含有这三个片段之一的Bac⁻转化体。pKSH1和pNP2的限制性图谱比较显示，两个质粒共有一个18.4 kb的区域，涉及三个BclI片段中的两个。与含有131.1 kb Bac质粒的菌株相比，乳酸乳球菌KSH1对指示菌株双乙酰乳酸链球菌18 - 16也表现出更强的抑制活性。
