Reduced Enterotoxin D Formation on Boiled Ham in Staphylococcus aureus Δagr Mutant
1
Applied Microbiology, Department of Chemistry, Lund University, SE-221 00 Lund, Sweden
2
Institute for Food Safety and Hygiene, University of Zurich, CH-8057 Zurich, Switzerland
*
Author to whom correspondence should be addressed.
Academic Editor: Scott A. Waldman
Toxins 2017, 9(9), 263; https://doi.org/10.3390/toxins9090263
Received: 4 August 2017
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Revised: 21 August 2017
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Accepted: 24 August 2017
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Published: 25 August 2017
(This article belongs to the Special Issue Heat-Stable Enterotoxins)
Staphylococcal food poisoning (SFP) is a common cause of foodborne illness worldwide, and enterotoxin D (SED) is one of the most frequent Staphylococcus aureus enterotoxins associated with it. It has been reported that the expression and formation of SED in S. aureus is regulated by the quorum sensing Agr system. In this study, the effect of agr deletion on sed expression in S. aureus grown on boiled ham was investigated. Growth, sed mRNA and SED protein levels in an S. aureus wild type strain and its isogenic Δagr mutant were monitored for 14 days at 22 °C. The results showed that although deletion of the agr gene did not affect the growth rate or maximum cell density of S. aureus on boiled ham, it had a pronounced effect on SED formation during the first 5 days of incubation. The SED concentration was not reflected in the amount of preceding sed transcripts, suggesting that sed transcription levels may not always reflect SED formation. The expression of RNAIII transcript, the regulatory signal of the Agr system, was also monitored. Similar transcription patterns were observed for RNAIII and sed. Surprisingly, in the Δagr mutant, sed expression was comparable to that in the wild type strain, and was thus unaffected by deletion of the Agr system. These results demonstrate that the Agr system appears to only partially affect SED formation, even in a real food environment.
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Keywords:
Staphylococcus aureus; staphylococcal food poisoning; SED formation; Agr quorum sensing system; RNAIII; boiled ham
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MDPI and ACS Style
Susilo, Y.B.; Sihto, H.-M.; Rådström, P.; Stephan, R.; Johler, S.; Schelin, J. Reduced Enterotoxin D Formation on Boiled Ham in Staphylococcus aureus Δagr Mutant. Toxins 2017, 9, 263. https://doi.org/10.3390/toxins9090263
AMA Style
Susilo YB, Sihto H-M, Rådström P, Stephan R, Johler S, Schelin J. Reduced Enterotoxin D Formation on Boiled Ham in Staphylococcus aureus Δagr Mutant. Toxins. 2017; 9(9):263. https://doi.org/10.3390/toxins9090263
Chicago/Turabian StyleSusilo, Yusak B., Henna-Maria Sihto, Peter Rådström, Roger Stephan, Sophia Johler, and Jenny Schelin. 2017. "Reduced Enterotoxin D Formation on Boiled Ham in Staphylococcus aureus Δagr Mutant" Toxins 9, no. 9: 263. https://doi.org/10.3390/toxins9090263
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