Antimicrobial and antibiofilm potential of Streptomyces sp. metabolites against Staphylococcus aureus

Abstract

Abstract This study evaluated the antimicrobial and antibiofilm activities of metabolites produced by a Streptomyces strain isolated from impacted soil against Staphylococcus aureus. The study employed the Streptomyces sp. SLA3 strain. Secondary metabolites were obtained through submerged fermentation followed by liquid-liquid extraction. Chemical characterization was performed using gas chromatography coupled with mass spectrometry (GC-MS). The pathogenic models included S. aureus ATCC 25923 and five clinical isolates. Antimicrobial activity was assessed by the agar diffusion method and determination of minimum inhibitory concentration (MIC). Antibiofilm activity was evaluated through inhibition of biofilm formation and eradication of preformed biofilms. Toxicity evaluation was conducted using Tenebrio molitor larvae and hemolytic activity assays. Chemical characterization of the extract revealed a predominance of 2,4-bis(1,1-dimethylethyl)phenol and long-chain saturated fatty acids (myristic, palmitic, and stearic acids). Inhibition halos reached approximately 35 mm, and MIC values ranged from 1,000 to 2,000 μg/mL. The S. aureus CIBC 9722 strain exhibited significant inhibition of biofilm formation (p < 0.05). For S. aureus ATCC 25923, S. aureus CIBC 9722, S. aureus CIBC 20, and S. aureus CIBC 14, all extract concentrations promoted a significant reduction in preformed biofilms (p < 0.05). In the toxicity assay using T. molitor larvae, groups treated with extract concentrations of 1,000-500 µg/mL exhibited a survival rate of 75%. The effective concentration required to induce 50% hemolysis (HC50) was estimated at 329.9 µg/mL. These findings highlight the biotechnological potential of metabolites from Streptomyces sp.