Inhibitory Effect of the Brown Seaweed Sargassum angustifolium Extraction on Growth and Virulence Factors of Staphylococcus aureus

Regarding the growing trend of multidrug resistant strains of Staphylococcus aureus, the search for alternative and novel antimicrobial agent has been intensified. For this purpose, the present study was carried out to investigate the antagonistic effect of the brown seaweed Sargassum angustifolium on growth and virulence factors of S. aureus. A typical microdilution assay was performed to monitor inhibitory effect of S. angustifolium extraction on growth of the bacteria within a 6-h period. Furthermore, Real-Time PCR assay with specific primers was conducted to evaluate the impact of extraction on expression of genes encoding staphylococcal enterotoxins (sea) and capsule formation (cap8). The results revealed that S. angustifolium extract inhibited bacterial growth in a dose-dependent way; so that bacterial growth was fully stopped at the end of the assay. Antibacterial effect was enhanced by increasing in S. angustifolium extraction concentration. The results of Real-Time PCR assay indicated seaweed extraction was able to decrease virulence genes expression significantly. Again, by increasing extraction concentration, stronger inhibitory effect was observed. As a whole, the findings of this study suggest that S. angustifolium extract has potent antimicrobial effect that can be used for development of new generation of anti-staphylococcal medicines.