Mutations that affect the regulation of phs in Salmonella typhimurium

Abstract

The regulation of p h [production of hydrogen sulphide (H2S)] in Salmonella v p h u r i u m is complex. Previous studies have shown that expression is dependent upon the presence of reduced sulphur and anaerobimis and is modulated by carbon source and growth stage. Transposon mutagenesis failed to find any potential tram-acting factors effective in the regulation ofphs in relation to oxygen. Spontaneous mutants capable of expressingplks-lac aerobically were isolated and characterized. These mutations are closely linked to p h and d e c t not only oxygen regulation but also the requirement for cyclic AMP and reduced sulphur. Analysis of merodiploid strains indicates that these mutations are &acting and that phs is not subject to autoregulation.

Genetic Analysis of Non-Hydrogen Sulfide-Producing Salmonella enterica Serovar Typhimurium and S. enterica Serovar Infantis Isolates in Japan

“…1; also, see Tables S2 and S3 in the supplemental material). The phs genes are essential for the dissimilatory anaerobic reduction of thiosulfate to H 2 S in S. Typhimurium (4,5), suggesting that the disruption of the phsA gene could be involved in H 2 S production. Intriguingly, a nonsense mutation in the phsA gene was also identified in low-H 2 S-producing S. enterica serovar Paratyphi A (AKU_12601 and ATCC 9150) (6); thus, comparative genomic analysis also supports our findings.…”