Identification of Salmonella typhimurium Genes Required for Colonization of the Chicken Alimentary Tract and for Virulence in Newly Hatched Chicks

Abstract

ABSTRACT From a collection of 2,800 Tn 5 -TC1 transposon mutants of Salmonella typhimurium F98, 18 that showed reduced intestinal colonization of 3-week-old chicks were identified. The sites of transposon insertion were determined for most of the mutants and included insertions in the lipopolysaccharide biosynthesis genes rfaK , rfaY , rfbK , and rfbB and the genes dksA , clpB , hupA , and sipC . In addition, identification was made of an insertion into a novel gene that encodes a protein showing similarity to the IIC component of the mannose class of phosphoenolpyruvate-carbohydrate phosphotransferase systems, which we putatively called ptsC . Transduction of most of the transposon mutations to a fresh S. typhimurium F98 genetic background and construction of defined mutations in the rfbK , dksA , hupA , sipC , and ptsC genes of S. typhimurium F98 supported the role in colonization of all but the pts locus. The virulence of the rfbK , dksA , hupA , sipC , and ptsC defined mutants and clpB and rfaY transductants in 1-day-old chicks was tested. All but the ptsC and rfaY mutants were attenuated for virulence. A number of other phenotypes associated with some of the mutations are described.