Kojic Milan, Strahinic Ivana, Fira Djordje, Jovcic Branko, Topisirovic Ljubisa
Institute of Molecular Genetics and Genetic Engineering, Belgrade, Serbia and Montenegro.
Can J Microbiol. 2006 Nov;52(11):1110-20. doi: 10.1139/w06-072.
In this study, the plasmid content and bacteriocin production of natural isolates of lactococci were investigated. Five bacteriocin producing lactococcal strains (Lactococcus lactis subsp. lactis BGMN1-2, BGMN1-3, BGMN1-5, BGMN1-6, and BGMN2-7) were isolated as nonstarter microflora of semi-hard homemade cheese and characterized. All isolates contained a number of plasmids. It was shown that lcnB structural genes for bacteriocin lactococcin B were located on large plasmids in all isolates. In the strains BGMN1-3 and BGMN1-5 proteinase prtP genes collocated with lcnB. Furthermore, these strains produced two additional bacteriocins (LsbA and LsbB) with genes responsible for their production and immunity located on the small rolling circle-replicating plasmid pMN5. Using deletion experiments of pMN5, minimal replicon of the plasmid and involvement of a bacteriocin locus in plasmid maintenance were identified. In addition, plasmid curing experiments showed that genes for catabolism or transport of 10 carbohydrates in the strain BGMN1-5 were plasmid located.
在本研究中，对乳酸乳球菌天然分离株的质粒含量和细菌素产生情况进行了调查。从半硬质自制奶酪的非发酵剂微生物菌群中分离出五株产细菌素的乳酸乳球菌菌株（乳酸乳球菌乳酸亚种BGMN1-2、BGMN1-3、BGMN1-5、BGMN1-6和BGMN2-7）并进行了鉴定。所有分离株都含有若干质粒。结果表明，细菌素乳酸乳球菌素B的lcnB结构基因位于所有分离株的大质粒上。在BGMN1-3和BGMN1-5菌株中，蛋白酶prtP基因与lcnB位于同一位置。此外，这些菌株还产生了另外两种细菌素（LsbA和LsbB），其产生和免疫相关基因位于小的滚环复制质粒pMN5上。通过对pMN5进行缺失实验，确定了该质粒的最小复制子以及一个细菌素基因座在质粒维持中的作用。此外，质粒消除实验表明，BGMN1-5菌株中10种碳水化合物的分解代谢或转运基因位于质粒上。
