Journal of Southern Medical University ›› 2006, Vol. 26 ›› Issue (06): 839-842.

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Screening, isolation and identification of nisin resistance determinant gene in strains of Lactococcus lactis

YUN Xue-xia, HU Jing, CHEN Qing Department of Epidemiology, Southern Medical University, Guangzhou 510515, China   

  1. 南方医科大学公共卫生与热带医学学院流行病教研室; 南方医科大学公共卫生与热带医学学院流行病教研室 广东广州510515; 广东广州510515;
  • Online:2006-06-20 Published:2006-06-20

Abstract: Objective To isolate and identify nisin resistance determinant (NSR) gene from Lactococcus lactis. Methods The Lactococcus lactis strains harboring NSR gene were isolated from different milk samples by selective culture supplemented with nisin and confirmed by PCR detection of 16S rRNA. Nisin resistance determinant gene was determined by PCR amplification, enzyme digestion and sequencing. Results Thirty nisin-resistant Lactococcus lactis strains from fresh milk samples were obtained. Three of these strains contained NSR gene of about 1000 bp as determined by agarose gel electrophoresis and further confirmed by enzyme digestion and sequence analysis. The NSR gene was located on the plasmid of Lactococcus lactis. Conclusion Complete NSR gene, located on the bacterial plasmid, has been successfully isolated from nisin-resistant Lactococcus lactis strains from fresh milk. 

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