title: Competition among isolates of Salmonella enterica ssp. enterica serovar Typhimurium: role of prophage/phage in archived cultures.
abstract: Previously, we reported extensive diversity among survivors of Salmonella enterica ssp. enterica serovar Typhimurium that were stored for four decades in sealed agar stabs. Thus raising the question: was there selection for greater fitness among eventual survivors? To address this, we cocultured archived LT2 survivors with nonarchived (parental) LT2 strains in competition experiments. Selected archived strains outgrew a nonarchived LT2 sequenced strain. Although we initially assumed this was the result of mutations empowering greater nutritional utilization, we found phage selection was also involved. Phage fels-1 and fels-2 in supernatants were identified by primer/PCR as a putative selective force following single plaque isolations on a prophage-free strain and testing on appropriate hosts. In confirmatory experiments, instead of coculture in Luria-Bertani requiring antibiotic marker insertions, competing strains without markers were inoculated at opposite edges of motility plates. Not only did the archived LT2 population overgrow the nonarchived LT2 population, but also clear zones appeared at edges of encounters from which phage fels-1 and fels-2 (but not gifsy-1 nor gifsy-2) were recovered. However, in competitions of an archived strain with S. Typhimurium ATCC 14028, phage emerged that had a DNA base sequence segment of prophage ST64B but the sequence differed from the reported homologous segment in ST64B.
authors.affiliation: Cancer Research Center, Columbia, MO 65201, USA.
authors.forename: Michelle
authors.initials: M
authors.lastname: Erickson
authors.forename: Dustin
authors.initials: D
authors.lastname: Newman
authors.forename: Richard Allen
authors.initials: RA
authors.lastname: Helm
authors.forename: Alison
authors.initials: A
authors.lastname: Dino
authors.forename: Michael
authors.initials: M
authors.lastname: Calcutt
authors.forename: Wendell
authors.initials: W
authors.lastname: French
authors.forename: Abraham
authors.initials: A
authors.lastname: Eisenstark
mesh_terms: D000898:Antibiosis; D001433:Bacteriolysis; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D039002:Prophages / Q000235:genetics / Q000254:growth & development*; D012483:Salmonella Phages / Q000235:genetics / Q000254:growth & development*; D012486:Salmonella typhimurium / Q000254:growth & development / Q000502:physiology* / Q000821:virology*; D017422:Sequence Analysis, DNA; D010948:Viral Plaque Assay
chemical_list: D004279:DNA, Viral