Serovar Typhimurium enterica

摘要: MATERIALS AND METHODSBacterial strains and phage. All S. enterica serovar Typhimurium strains used in this study were derived from strain ATCC 14028 (CDC 6516-60) and are listed in Table 1. The high-frequency generalized transducing bacteriophage P22 mutant HT105/1, int-201, was used for all transductional crosses (47), and phagefree, phage-sensitive transductants were isolated as previously described (5). The isolations of all ivi fusions used in this study were described previously (19). Bacteriophage P22-3657 and S. enterica serovar Typhimurium LT2 strain MST3357 were kindly provided by Stan Maloy. P22-3657 contains a deletion in gene 9, encoding phage P22 tail protein (15). MST3357 constitutively expresses P22 tail protein, which is necessary for P22-3657 to form plaques. Nomenclature. The nomenclature is generally as described previously (4, 7, 13). Unless otherwise specified, the mutation designations used in this study are those of Sanderson et al.(45). The nomenclature z--:: Tn10 refers to a Tn10 insertion in a “silent” DNA region; the z--describes the map position of the insertion (44). The nomenclature used for chromosomal rearrangements is as described previously (8, 21, 33, 48).Media and chemicals. Luria broth (LB)(11) was the laboratory medium used in this study except for-galactosidase assays, for which 2-(N-morpholino) ethanesulfonic acid (MES) buffered to pH 5.5 and supplemented with 0.05 mM Mg2 was used. Unless otherwise specified, the final concentrations of antibiotics were as follows: ampicillin, 50 g/ml (LB) or 16 g/ml (MES); kanamycin, 50 g/ml; and tetracycline, 20 g/ml. Mitomycin C and o …