Investigation of antibacterial and anti-cancer activities of Streptomyces sp SRF1 culture filtrate

摘要

Purpose: To evaluate the antibacterial activity and cytotoxic effects of Streptomyces sp. SRF1 culture filtrate extract against breast cancer cell line. Methods: The activity of the extract against Gram-positive and Gram-negative bacteria was initially screened by an agar-well diffusion method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were measured by broth microdilution method. Time-kill assays were also performed, and extract-induced morphological and ultrastructural changes to bacterial cells were investigated. Sulforhodamine B (SRB) assay was performed to determine the cytotoxicity of the extract against the human breast cancer cell line, MCF-7. Results: Antibacterial activity by the extract was detected against four strains of Gram-positive pathogens including one strain of methicillin-susceptible Staphylococcus aureus (MSSA) and 3 strains of methicillin-resistant Staphylococcus aureus (MRSA) - with low MIC and MBC values. This activity was bactericidal after 6 h exposure. Morphological alterations were detected on the cell surface of both MSSA and MRSA. The extract also inhibited MCF-7 cell growth with half-maximal concentration (IC 50 ) of 211.67 ± 33.95 μg/mL in 72 h. Conclusions: Streptomyces sp. SRF1 culture filtrate extract exhibits potent antibacterial and anticancer activities and thus, represents a potential source of antibacterial and anticancer drugs.