Methanol Crude Extract Derived from Streptomyces sp. PFK4: Antimicrobial, Antioxidant Properties, Potential Modes of Action, and Chemical Profile of Bioactive Compounds

Bacteria of the Streptomyces genus are a promising source of bioactive products, with several applications.This study aimed to evaluate the antimicrobial and antioxidant properties of the methanol crude extract of Streptomyces sp.PFK4, its modes of action, and bioactive metabolites.Zone of inhibition (ZI), minimum inhibition concentration (MIC), and minimum bactericidal concentration (MBC) were conducted to determine antibacterial activity.Bacterial cell and protein synthesis were assayed as potential modes of action of extract.The antioxidant properties were determined by 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), 2,2-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging and Ferric reducing assays (FRAP).The gas chromatographymass spectrometry (GC-MS) was used to identify bioactive compounds.The mean ZI ranged from 11.000.33 to 20.600.88 mm with the highest ZI observed against Salmonella typhi and Staphylococcus aureus.The MIC ranged from 0.25 to 0.5 mg/mL and MBC from 0.25 to 2 mg/mL against bacterial pathogens.The crude methanol extract of Streptomyces sp.PFK4 showed the ability to inhibit Escherichia coli cell from 100 to 60.17% while protein synthesis was from 5.45 to 5.17 g Eq BSA/g.It also exhibited DPPH and ABTS scavenging activities at concentrations of 50 g/mL with the highest inhibition concentration of 83.74 2.10% and 72.97 2.67%, IC50 values of 100.8 g/mL and 15.69 g/mL respectively.The highest FRAP was 8.04 0.85 g/mL at a 200 g/mL concentration.From the GC-MS analysis, twenty-three biological compounds primarily fatty acids or their esters were identified.This study demonstrates the methanol crude extract of Streptomyces sp.PFK4 possesses antibacterial and antioxidant activities; inhibits bacterial cell and protein synthesis ability; and contains mostly fatty acids and their derivatives recognized as therapeutic agents.