Abstract
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 (IC50) 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.Keywords: Antibacterial activity, Anti-breast cancer, Staphylococcus aureus, Streptomyces sp. SRF1
Highlights
Soil microorganisms are an interesting source of new bioactive compounds
SRF1 culture filtrate extract was investigated against 16 strains of human pathogenic bacteria
The extract inhibited the growth of 4 strains of Gram positive staphylococci, with large inhibition zone diameters compared to the control antibiotics tetracycline and ciprofloxacin
Summary
Soil microorganisms are an interesting source of new bioactive compounds. Compounds produced by such organisms can be developed and used in both agriculture and medicine [1,2]. Actinomycetes are soil bacteria known to produce various novel bioactive compounds. They are present in nature in a wide range of habitats, exhibit considerable species diversity, and considerable diversity in terms of their morphology, physiology, and biochemical activities [3]. Other soil Streptomyces spp. such as S. antibioticus, S. flaveolus and S. psammoticus have been shown to inhibit MRSA [13]
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