Effect of sodium nitrite and regulatory mutations Δagr, ΔsarA, and ΔsigB on the mRNA and protein levels of staphylococcal enterotoxin D. (July 2016)

• Record Type: Journal Article
• Authors: Sihto, Henna-Maria; Budi Susilo, Yusak; Tasara, Taurai; Rådström, Peter; Stephan, Roger; Schelin, Jenny; Johler, Sophia
• Is Part Of: Food control. Volume 65(2016:Jul.)
• Page Start: 37
• Page End: 45
• Publication Date: 2016-07
• Subjects: Staphylococcus aureus -- sed expression -- Enterotoxin D formation -- Sodium nitrite -- Regulatory response; Food -- Quality -- Periodicals; Food -- Analysis -- Periodicals; Food handling -- Periodicals; Food industry and trade -- Quality control -- Periodicals; Aliments -- Industrie et commerce -- Qualité -- Contrôle -- Périodiques; Aliments -- Qualité -- Périodiques; Aliments -- Analyse -- Périodiques; Hygiène alimentaire -- Périodiques; Food -- Analysis; Food handling; Food -- Quality; Periodicals; Electronic journals; 664.07
• DOI: 10.1016/j.foodcont.2016.01.007
• Languages: English
• ISSNs: 0956-7135

Abstract

Abstract: Staphylococcal food poisoning results from ingestion of enterotoxins produced by Staphylococcus aureus . Staphylococcal enterotoxin D (SED) is one of the most common toxins detected in S. aureus strains associated with intoxications. The effect of sodium nitrite on enterotoxin production has been only partly investigated, despite its wide usage in meat products. In addition, the factors influencing SED regulation are unclear. The aim of this study was to determine the effect of sodium nitrite on sed transcription and SED production, as well as the effect of regulatory mutations on SED protein levels. Temporal sed mRNA and SED protein levels were compared in LB and LB supplemented with 150 mg/L nitrite, and SED protein levels between wild type (wt) and isogenic regulatory mutants (Δ agr, Δ sarA, Δ sigB ) under control and sodium nitrite conditions. Relative sed mRNA levels of wt strains were higher in late stationary phase in the presence of nitrite compared to control conditions. However, SED protein levels were decreased in the presence of nitrite. In LB, Δ agr mutants showed SED levels similar to the wt, while Δ sarA mutants exhibited reduced and Δ sigB mutants increased SED levels compared to the wt. In LB with sodium nitrite, SED levels of mutant strains were reduced similar to the wt strains, except for two Δ agr mutants, in which SED levels were increased in the presence of nitrite. Overall, strain-specific variation with regard to the effect of regulatory mutations was observed. In addition, the data suggests that SED regulation may not be as tightly dependent on Agr as previously described. Highlights: Enterotoxin D production is decreased in the presence of nitrite (c = 150 mg/L). Staphylococcus aureus growth is not significantly affected by nitrite (c = 150 mg/L). Alternative sigma factor B has an essential role in enterotoxin D regulation. Staphylococcal accessory regulator A positively regulates enterotoxin D production. Loss of accessory gene regulator does not alter enterotoxin D production.