The location of four fimbrin-encoding genes, agfA, fimA, sefA and sefD, on the Salmonella enteritidis and/or S. typhimurium XbaI-BlnI genomic restriction maps

Abstract Four fimbrin-encoding genes, fimA (type-1 or SEF21 fimbriae), agfA (thin aggregative or SEF17 fimbriae), sefA (SEF14 fimbriae) and sefD (SEF18 fimbriae) from Salmonella enteritidis (Se) 27655-3b were located onto the Xba I- Bln I genomic restriction maps of Salmonella typhimurium (St) LT2 and Se strains SSU7998 and 27655-3b. The Xba I or Bln I genomic fragments carrying these genes were identified by hybridization with labeled oligodeoxyribonucleotides or fimbrin-encoding genes. The fimbrin-encoding genes were not encoded by the virulence plasmids, but were located on chromosomal DNA fragments. The position of each gene on a given Xba I fragment was determined by hybridization of a series of Xba I-digested genomic DNA samples from previously characterized Tn 10 mutants of Se and St with its respective probe. The fimA gene mapped near 13 centisomes (Cs) between purE 884::Tn 10 at 12.6 Cs (11.8 min) and apeE2::Tn 10 at 12.8 Cs (12.3 min) beside the first Xba I site at 13.0 Cs in St or between purE884::Tn 10 at 12.6 Cs and the Xba I site at 13.6 Cs in Se. The agfA gene mapped near 26 Cs between putA::Tn 10 and pyrC691::Tn 10 in St, but near 40 Cs between pncX::Tn 10 and the Xba I site at 43.3 Cs in Se. This difference in map position was due to the location of agfA near one end of the 815-kb chromosomal fragment inverted between Se and St. The sefA and sefD genes mapped precisely at 97.6 Cs in Se , but were absent from the genome of St LT2. To verify the mapping procedures used herein, tctC was also mapped in both Salmonella serovars. As expected, tctC mapped near 60 Cs in both St and Se, thereby confirming previous studies