Competition among isolates ofSalmonella entericassp.entericaserovar 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.

Multicellular Bacteria Deploy the Type VI Secretion System to Preemptively Strike Neighboring Cells

“…[33], [34], [35]. However, this phenomenon, known as colony incompatibility, is thought to be due to bacteriophages, bacteriocins, or through production and excretion of antibiotics [33], [34].…”

Characterization and Comparative Genomic Analysis of a Novel Bacteriophage, SFP10, Simultaneously Inhibiting both Salmonella enterica and Escherichia coli O157:H7

“…The bacterial strains used in this study are listed in Table 1. Prophage-cured Salmonella enterica serovar Typhimurium strain LT2 (19) from the Cancer Research Center (Colombia, MO) was used for isolation of Salmonella-infecting phages from the collected slurry samples. All bacteria listed in Table 1 were grown at 37°C for 12 h in Luria-Bertani (LB) broth medium (Difco, Detroit, MI).…”

Core Lipopolysaccharide-Specific Phage SSU5 as an Auxiliary Component of a Phage Cocktail for Salmonella Biocontrol

“…Bacterial strains used for the host range test and the receptor determination are listed in Tables 1 and 2, respectively. The prophage-cured Salmonella enterica serovar Typhimurium LT2 strain [designated LT2(c)], which was obtained from the Cancer Research Center, Columbia, MO (25), and its derivatives were used to isolate and propagate bacteriophages. All bacterial strains were aerobically grown at 30°C or 37°C in Luria-Bertani (LB) broth or agar (supplemented with 1.5% agar).…”