Temporal expression of the staphylococcal enterotoxin D gene under NaCl stress conditions

Sihto, Henna-Maria; Tasara, Taurai; Stephan, Roger; Johler, Sophia

doi:10.1093/femsle/fnv024

Cited by 21 publications

(24 citation statements)

References 34 publications

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“…Pronounced strain-specific variation of SE mRNA and protein levels has been reported, in particular under conditions of environmental stress encountered in the food matrix [ 3 , 4 , 5 , 6 ]. Expression of the phage-encoded SEA was shown to be linked to the life cycle of the phage [ 7 , 8 ] and to nucleotide sequence variation in the sea gene and upstream promoter region [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

Sequence Variability in Staphylococcal Enterotoxin Genes seb, sec, and sed

Johler

Sihto

Macori

et al. 2016

Toxins

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Ingestion of staphylococcal enterotoxins preformed by Staphylococcus aureus in food leads to staphylococcal food poisoning, the most prevalent foodborne intoxication worldwide. There are five major staphylococcal enterotoxins: SEA, SEB, SEC, SED, and SEE. While variants of these toxins have been described and were linked to specific hosts or levels or enterotoxin production, data on sequence variation is still limited. In this study, we aim to extend the knowledge on promoter and gene variants of the major enterotoxins SEB, SEC, and SED. To this end, we determined seb, sec, and sed promoter and gene sequences of a well-characterized set of enterotoxigenic Staphylococcus aureus strains originating from foodborne outbreaks, human infections, human nasal colonization, rabbits, and cattle. New nucleotide sequence variants were detected for all three enterotoxins and a novel amino acid sequence variant of SED was detected in a strain associated with human nasal colonization. While the seb promoter and gene sequences exhibited a high degree of variability, the sec and sed promoter and gene were more conserved. Interestingly, a truncated variant of sed was detected in all tested sed harboring rabbit strains. The generated data represents a further step towards improved understanding of strain-specific differences in enterotoxin expression and host-specific variation in enterotoxin sequences.

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Section: Introductionmentioning

confidence: 99%

Sequence Variability in Staphylococcal Enterotoxin Genes seb, sec, and sed

Johler

Sihto

Macori

et al. 2016

Toxins

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“…As demonstrated in different studies, food-related stress conditions, such as NaCl, nitrite, glucose and lactic acid variations encountered during food production and preservation, can induce significant changes in the activity of SEB and SED promoter genes [117,118]. In this study six batches of cheese naturally contaminated with S. aureus strains were produced.…”

Section: Discussionmentioning

confidence: 96%

Genome-Wide Profiling of Enterotoxigenic Staphylococcus aureus Strains Used for the Production of Naturally Contaminated Cheeses

Macori

Bellio

Bianchi

et al. 2019

Genes

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Staphylococcus aureus is a major human pathogen and an important cause of livestock infections. More than 20 staphylococcal enterotoxins with emetic activity can be produced by specific strains responsible for staphylococcal food poisoning, one of the most common food-borne diseases. Whole genome sequencing provides a comprehensive view of the genome structure and gene content that have largely been applied in outbreak investigations and genomic comparisons. In this study, six enterotoxigenic S. aureus strains were characterised using a combination of molecular, phenotypical and computational methods. The genomes were analysed for the presence of virulence factors (VFs), where we identified 110 genes and classified them into five categories: adherence (n = 31), exoenzymes (n = 28), genes involved in host immune system evasion (n = 7); iron uptake regulatory system (n = 8); secretion machinery factors and toxins’ genes (n = 36), and 39 genes coding for transcriptional regulators related to staphylococcal VFs. Each group of VFs revealed correlations among the six enterotoxigenic strains, and further analysis revealed their accessory genomic content, including mobile genetic elements. The plasmids pLUH02 and pSK67 were detected in the strain ProNaCC1 and ProNaCC7, respectively, carrying out the genes sed, ser, and selj. The genes carried out by prophages were detected in the strain ProNaCC2 (see), ProNaCC4, and ProNaCC7 (both positive for sea). The strain ProNaCC5 resulted positive for the genes seg, sei, sem, sen, seo grouped in an exotoxin gene cluster, and the strain ProNaCC6 resulted positive for seh, a transposon-associated gene. The six strains were used for the production of naturally contaminated cheeses which were tested with the European Screening Method for staphylococcal enterotoxins. The results obtained from the analysis of toxins produced in cheese, combined with the genomic features represent a portrait of the strains that can be used for the production of staphylococcal enterotoxin-positive cheese as reference material.

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“…This is a CC8/t648 strain isolated from food and the feces of an SFP patient in Germany in 2007. An isogenic agr deletion mutant RKI1Δ agr was constructed by transduction using phage 80α, as described previously [ 22 , 40 ]. Strains were stored as glycerol stocks at −80 °C and were resuscitated by streaking on brain heart infusion (BHI) agar (Difco Laboratories; BD Diagnostic Systems, Le Pont de Claix, France) or BHI agar supplemented with erythromycin (10 µg × mL −1 , Sigma-Aldrich, Stockholm, Sweden).…”

Section: Methodsmentioning

confidence: 99%

“…RNAIII indirectly induces sed expression by repressing the repressor of toxins (Rot) [ 21 ]. The influence of the global Agr regulatory system and numerous food-related stresses including NaCl, nitrite, glucose, and lactic acid on sed expression has so far been studied exclusively using planktonic growth in cultivation broth [ 14 , 16 , 17 , 18 , 19 , 21 , 22 , 23 , 24 , 25 ].…”

Section: Introductionmentioning

confidence: 99%

Reduced Enterotoxin D Formation on Boiled Ham in Staphylococcus aureus Δagr Mutant

Susilo

Sihto

Rådström

et al. 2017

Toxins

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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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Temporal expression of the staphylococcal enterotoxin D gene under NaCl stress conditions

Cited by 21 publications

References 34 publications

Sequence Variability in Staphylococcal Enterotoxin Genes seb, sec, and sed

Sequence Variability in Staphylococcal Enterotoxin Genes seb, sec, and sed

Genome-Wide Profiling of Enterotoxigenic Staphylococcus aureus Strains Used for the Production of Naturally Contaminated Cheeses

Reduced Enterotoxin D Formation on Boiled Ham in Staphylococcus aureus Δagr Mutant

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