Impact of the Food-Related Stress Conditions on the Expression of Enterotoxin Genes among Staphylococcus aureus

Abstract

Staphylococcus aureus is one of the most important foodborne pathogens. S. aureus has the capability to produce a variety of toxins, including staphylococcal enterotoxins (SEs). The aim of this study was to evaluate the survival rate of S. aureus cells and analyze enterotoxins gene expression after exposure to osmotic stress and acidic/alkaline stress. To determine survival rates, the traditional plate counting method and flow cytometry were used. The expression levels of the enterotoxin genes were performed by quantitative reverse transcription PCR (RT-qPCR). Expression changes differed depending on the stressors chosen. The obtained results in this study showed the effect of critical food-related stress conditions on SE gene expression in S. aureus. The study showed different expression levels of the tested enterotoxins genes depending on the stress. The most tested enterotoxin genes (seg, sei, and selo) after exposure to pH = 4.5 stress have similar expression as in the optimal condition. After alkaline treatment (pH = 9.6), a similar expression gene value as for the optimal condition was observed. The analysis of gene expression in response to stress caused by NaCl, showed that the expression of selp decreased, whereas selu, selm, and selo genes increased. A significantly decreased expression of the sea gene was observed.

Genetic Complexity of CC5 Staphylococcus aureus Isolates Associated with Sternal Bursitis in Chickens: Antimicrobial Resistance, Virulence, Plasmids, and Biofilm Formation

“…Leukocidin ED (LukED) is a potent pore-forming toxin produced by S. aureus , and it functions by lysing host cells, thereby enhancing bacterial virulence [ 61 ]. Based on antigenic diversity, researchers have identified over 20 different staphylococcal enterotoxins (SEs), ranging from SEA to SElV [ 62 , 63 ]. These enterotoxins possess the ability to stimulate large populations of T cells, resulting in an uncontrolled activation of the immune system [ 64 ].…”

“…Staphylococcal food poisoning is primarily caused by SEs. Upon ingestion of food contaminated with these toxins, individuals may experience acute gastroenteritis, diarrhea, vomiting, and abdominal pain [ 62 , 63 ]. All isolates also carried serine protease genes ( spl A and spl B), one intercellular adhesin gene ( ica C), and an antiphagocytic fibrinogen gene ( sem ).…”