Effect of Rosmarinus officinalis L. essential oil on growth and enterotoxin A, C and E production of Staphylocuccus aureus ATCC 29213

Staphylococcal food poisoning is resulted from the consumption of a food in which enterotoxigenic staphylococci have grown and produced toxins. Targeting bacterial virulence factors is now gaining interest as an alternative strategy to develop new types of antimicrobial preservatives. The purpose of this study was to determine the effect of R. officianalis L. (Ros) essential oil (EO) on growth and gene expression of enterotoxins A, C, and E in Staphylococcus aureus ATCC 29213. In this study, after determining the minimum inhibitory concentration, the growth and secretion of SEA, SEC, and SEE (detected by ELISA method) by S. aureus treated with graded subinhibitory concentrations of EO was evaluated. In addition, the influence of the EO on the transcription of sea, sec and see (the genes encoding SEA, SEC and SEE, respectively) was analyzed by quantitative RT-PCR. Ros EO at a concentration of 75% MIC, significantly, reduced the growth of S. aureus. EO inhibited the transcription of sea, sec and see in S. aureus, in a dose-dependent manner, resulting in a reduction of SEA, SEC and SEE secretion. These data suggest that the Ros EO may be useful as a natural preservative against the growth and enterotoxin production of S.aureus in food industry.