Abstract
The gene order and orientation in the leu-pyrA region of the Salmonella typhimurium linkage map was established by phage P22-mediated transductions. The gene order, in counterclockwise orientation, is leuO-leuA-leuB-leuC-leuD-ara-fol-pyrA . The fol locus is co-transducible with either the ara and leu loci or the pyrA locus, whereas no co-transduction for the ara and pyrA loci can be found.