Application of nucleotide sequence of RNA polymerase β-subunit gene (rpoB) to molecular differentiation of serovars of Salmonella enterica subsp enterica

To establish a molecular differentiation method for Salmonella enterica subsp. enterica, a hypervariable region of RNA polymerase P-subunit (rpoB) of S. enterica subsp. enterica (1), serotype Typhimurium, and Escherichia coli were investigated through comparison of nucleotide sequence of the region. The hyper-variable region was identified at 612-937 of the gene. After PCR amplification of the region in the 17 serotypes and two biotypes of serotype Gallinarum of S. enterica subsp. enterica (1), the nucleotide sequences of the region were determined and compared. All serotypes were distantly related to E. coli with 82.8-84.7% identities in nucleotide sequence while showing 96,6-100% identities with each other. According to the phylogenetic analysis based on the sequenced region with the neighbor-joining method, relatedness of biotype Gallinarum to serotype Enteritidis and biotype Pullorum was deter-mined. Biotype Gallinarum was more closely related to serotype Enteritidis than biotype Pullorum. These results suggested that the 612-937 variable region of rpoB might be useful for molecular evolutionary analysis of serotypes of S. enterica subsp. enterica (1). (C) 2001 Elsevier Science B.V. All rights reserved.