Prolonged expression and production of Staphylococcus aureus enterotoxin A in processed pork meat.

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Prolonged expression and production of Staphylococcus aureus enterotoxin A in processed pork meat. / Wallin, Nina; Marta, Dora; Borch, Elisabeth; Rådström, Peter.

I: International Journal of Food Microbiology, Vol. 141, 2010, s. S69-S74.

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T1 - Prolonged expression and production of Staphylococcus aureus enterotoxin A in processed pork meat.

AU - Wallin, Nina

AU - Marta, Dora

AU - Borch, Elisabeth

AU - Rådström, Peter

PY - 2010

Y1 - 2010

N2 - The bacteriophage-encoded staphylococcal enterotoxin A (SEA) is the toxin most frequently reported to be involved in staphylococcal food poisoning. In this study, sea expression and SEA formation were studied in four processed pork products: boiled ham, hot-smoked ham, Serrano ham (dry-cured Spanish ham) and black pepper salami. The products were selected because of their differences in intrinsic factors. As a reference, Staphylococcus aureus was cultivated under favorable planktonic growth conditions. Expression was mainly linked to bacterial growth for both meat products and broth cultures. In liquid broth, however, the relative level of sea mRNA peaked in the late exponential phase and then rapidly declined, while in the meat products allowing immediate growth, i.e. boiled and smoked ham, active sea expression occurred throughout the incubation period of seven days. Lower levels of sea mRNA and SEA were found in smoked ham compared to boiled ham, although viable counts of S. aureus on the two products were similar. Furthermore, the SEA concentration in the boiled ham reached a maximum after three days of incubation and then unpredictably decreased. In the Serrano ham, no increase in cell number was observed until day seven, and sea expression and extracellular SEA could only be detected on days five and seven. Finally, the black pepper salami with low pH and competing microbiota proved to be a difficult environment for the survival of S. aureus. The molecular mechanism behind the behaviour of S. aureus SEA expression is discussed in connection to the life-cycle of the SEA-encoding bacteriophage and the microbial communities in these pork products.

AB - The bacteriophage-encoded staphylococcal enterotoxin A (SEA) is the toxin most frequently reported to be involved in staphylococcal food poisoning. In this study, sea expression and SEA formation were studied in four processed pork products: boiled ham, hot-smoked ham, Serrano ham (dry-cured Spanish ham) and black pepper salami. The products were selected because of their differences in intrinsic factors. As a reference, Staphylococcus aureus was cultivated under favorable planktonic growth conditions. Expression was mainly linked to bacterial growth for both meat products and broth cultures. In liquid broth, however, the relative level of sea mRNA peaked in the late exponential phase and then rapidly declined, while in the meat products allowing immediate growth, i.e. boiled and smoked ham, active sea expression occurred throughout the incubation period of seven days. Lower levels of sea mRNA and SEA were found in smoked ham compared to boiled ham, although viable counts of S. aureus on the two products were similar. Furthermore, the SEA concentration in the boiled ham reached a maximum after three days of incubation and then unpredictably decreased. In the Serrano ham, no increase in cell number was observed until day seven, and sea expression and extracellular SEA could only be detected on days five and seven. Finally, the black pepper salami with low pH and competing microbiota proved to be a difficult environment for the survival of S. aureus. The molecular mechanism behind the behaviour of S. aureus SEA expression is discussed in connection to the life-cycle of the SEA-encoding bacteriophage and the microbial communities in these pork products.

U2 - 10.1016/j.ijfoodmicro.2010.03.028

DO - 10.1016/j.ijfoodmicro.2010.03.028

M3 - Article

VL - 141

SP - S69-S74

JO - International Journal of Food Microbiology

JF - International Journal of Food Microbiology

SN - 0168-1605

ER -