THE XBAI-BLNI-CEUI GENOMIC CLEAVAGE MAP OF SALMONELLA-ENTERITIDIS SHOWS AN INVERSION RELATIVE TO SALMONELLA-TYPHIMURIUM LT2

We have established the genomic cleavage map of Salmonella enteritidis strain SSU7998 using pulsed-field gel electrophoresis. The chromosome of 4600 kb was analysed by Xbal (16 fragments), I-Ceul (7 fragments) and BlnI (12 fragments); the genome also contains a plasmid of 60 kb. Cleavage sites of I-Ceul, in the large subunit ribosomal RNA gene, are conserved from Salmonella typhimurium and Escherichia coli K-12, and the Xbal and Blnl sites in glt-tRNA are also conserved, but other sites are less conserved. Transposon Tn10, located at 60 different positions in the chromosome of S. typhimurium, was transduced by bacteriophage P22 into S. enteritidis and the insertion mapped using the XbaI and BlnI sites on Tn10. Gene order in S. enteritidis is identical to S. typhimurium LT2 and similar to E. coli K-12 except for an inversion of 815 kb, which covers the terminus region including T1 and T2. Endpoints are in the NDZs, or non-divisible zones, in which inversion endpoints were not detected in experiments in E. coli K-12 and S. typhimurium LT2. This inversion resembles the inversion between S. typhimurium and E. coli, but is longer at both ends.