Venema K, Dost M H, Beun P A, Haandrikman A J, Venema G, Kok J
Department of Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands.
Appl Environ Microbiol. 1996 May;62(5):1689-92. doi: 10.1128/aem.62.5.1689-1692.1996.
Southern hybridization and PCR analysis were used to show that Lactococcus lactis IL1403, a plasmid-free strain that does not produce bacteriocin, contains genes on its chromosome that are highly homologous to lcnC and lcnD and encode the lactococcin secretion and maturation system. The lcnC and lcnD homologs on the chromosome of IL1403 were interrupted independently by Campbell-type integrations. Both insertion mutants were unable to secrete active lactococcin. Part of the chromosomal lcnC gene was cloned and sequenced. Only a few nucleotide substitutions occurred, compared with the plasmid-encoded lcnC gene, and these did not lead to changes in the deduced amino acid sequence. No genes homologous to those for lactococcin A, B, or M could be detected in IL1403, and the strain does not produce bacteriocin activity.
Southern杂交和PCR分析表明，乳酸乳球菌IL1403是一株不产细菌素的无质粒菌株，其染色体上含有与lcnC和lcnD高度同源的基因，编码乳球菌素的分泌和成熟系统。IL1403染色体上的lcnC和lcnD同源物通过Campbell型整合被独立中断。两个插入突变体均无法分泌活性乳球菌素。对染色体lcnC基因的一部分进行了克隆和测序。与质粒编码的lcnC基因相比，仅发生了少数核苷酸替换，且这些替换未导致推导的氨基酸序列发生变化。在IL1403中未检测到与乳球菌素A、B或M的基因同源的基因，且该菌株不产生细菌素活性。
