Antibacterial activity of Streptomyces sp. strain NELs-60 against Methicillin-resistant Staphylococcus aureus

Abstract Streptomyces sp. strain NELs-60 isolated from the coastal city Dongfang in Hainan province of China was investigated for its antibacterial potential. The isolate showed strong activity against Methicillin-resistant Staphylococcus aureus ATCC 43300. Using the Plackett Burman design, the culture condition was optimized to achieve the maximum production. Five variables and 12 run experiment were adopted, and the result evinced pH, inoculum time, and agitation speed highly influenced bioactive compound production. Solvent extraction method was applied for taking out of bioactive metabolites from the strain and highest activity was obtained from ethyl acetate. The active metabolites had obvious inhibitory effect, with MIC and MBC of 125 µg/mL and 500 µg/mL, respectively. Based on GC–MS, the active metabolites of NELs-60 were preliminarily analyzed. Different compounds were detected, suggesting their contribution towards the anti-MRSA activities. Ethyl acetate extract was found fully stable and showed decreases in biofilm formation, lower virulence and less toxicity when comparing on non-treated ones. The results of this study indicate the potential of NELs-60 as a promising source of anti-MRSA and antibiofilm compounds and warrants further study.