Specific and intraspecific molecular typing of lactococci based on polymorphism of DNA encoding rRNA

The rRNA gene restriction patterns or species of the genus Lactococcus were determined. Chromosomal DNA was digested with endonucleases and probed with radiolabelled DNA complementary to rRNA synthesized by random oligonucleotide priming using reverse transcriptase. Highly discriminatory restriction patterns were obtained which served to distinguish the five currently recognized lactococcal species. In addition the observed variations in the patterns at intra-specific level indicate that rRNA gene restriction fingerprinting may be of value in distinguishing the individual strains for epidemiological studies, and monitoring and checking authenticity of starter strains.