Regulatory and Enterotoxin Gene Expression and Enterotoxins Production in Staphylococcus aureus FRI913 Cultures...

The study aimed to examine the influence of a rotating magnetic field (RMF) of two different frequencies (5 and 50 Hz) on the expression of regulatory (agrA, hld, rot) and staphylococcal enterotoxin (SE-sea, sec, sel) genes as well as the production of SEs (SEA, SEC, SEL) by the Staphylococcus aureus FRI913 strain cultured on a medium supplemented with a subinhibitory concentration of trans-anethole (TA). Furthermore, a theoretical model of interactions between the bacterial medium and bacterial cells exposed to RMF was proposed. Gene expression and SEs production were measured using quantitative real-time PCR and ELISA techniques, respectively. Based on the obtained results, it was found that there were no significant differences in the expression of regulatory and SE genes in bacteria simultaneously cultured on a medium supplemented with TA and exposed to RMF at the same time in comparison to the control (unexposed to TA and RMF). In contrast, when the bacteria were cultured on a medium supplemented with TA but were not exposed to RMF or when they were exposed to RMF of 50 Hz (but not to TA), a significant increase in agrA and sea transcripts as compared to the unexposed control was found. Moreover, the decreased level of sec transcripts in bacteria cultured without TA but exposed to RMF of 50 Hz was also revealed. In turn, a significant increase in SEA and decrease in SEC and SEL production was observed in bacteria cultured on a medium supplemented with TA and simultaneously exposed to RMFs. It can be concluded, that depending on SE and regulatory genes expression as well as production of SEs, the effect exerted by the RMF and TA may be positive (i.e., manifests as the increase in SEs and/or regulatory gene expression of SEs production) or negative (i.e., manifests as the reduction in both aforementioned features) or none.