Determination of chromosome size and number of rrn loci in Lactobacillus plantarum by pulsed-field gel electrophoresis.

The size of the Lactobacillus plantarum CCM 1904 chromosome was determined by pulse-field gel electrophoresis. It was found to be 3.3-3.4 Mb using SfiI or AscI restriction endonucleases, compared to 3-4 Mb found for the other L. plantarum strains tested. L. plantarum CCM 1904 5S rDNA was clonedl by polymerase chain reaction, sequenced, and used as a probe to characterize strains. At least five rrn loci were found. The pulsed-field gel electrophoresis macrorestriction patterns were strain-specific, while the rDNA restriction hybridization patterns were species-specific.