PHYSICAL AND GENETIC CHROMOSOMAL MAPS OF STREPTOCOCCUS-AGALACTIAE, SEROTYPE-II AND SEROTYPE-III - RIBOSOMAL-RNA OPERON ORGANIZATION

A detailed analysis of two Streptococcus agalactiae (group B streptoco ccus, GBS) strains was performed by pulsed field gel electrophoresis ( PFGE). Digestion of the chromosomal DNA with SmaI and SgrAI endonuclea ses, followed by separation and analysis of fragments by PFGE was carr ied out. Physical chromosomal maps of serotype II/(alpha+beta) and III /alpha strains of S. agalactiae were constructed. The GBS genome size was estimated to be 2200 kb. Sixteen GBS genes were used as probes and were located on the restriction maps of both strains by DNA-DNA hybri dization. Six copies of ribosomal operons were found in the genome of the analyzed strains. Significant differences in the restriction patte rns of chromosomal DNA and DNA-DNA hybridization between the two analy zed strains were detected so that DNA restriction patterns may be used to trace outbreaks of disease. The overall GBS chromosomal organizati on as determined is fairly conserved. (C) 1998 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All righ ts reserved.