Antibacterial and anticancer properties of Streptomyces microflavus BA2 isolated from brackish waters

Abstract

The increasing incidence of cancer and the rapid emergence of antibiotic-resistant pathogens represent two of the greatest global health threats and necessitate safe, multifunctional agents. In the present study, the brackish water actinomycete Streptomyces microflavus BA2 was isolated from sediments of Lake Burullus (Egypt). Morphological and molecular analyses, including 16 S rRNA sequencing, confirmed its membership in the family Streptomycetaceae with 100% agreement to S. microflavus NRRL B-2156. The culture filtrate showed potent antibacterial activity against Staphylococcus aureus, Klebsiella pneumoniae, Proteus mirabilis, Salmonella typhi and Escherichia coli, with the aqueous diethyl ether fraction exhibiting the highest inhibition. GC-MS analyses identified seven bioactive compounds, including five fatty acids with antibacterial and anticancer properties, as well as phenolic derivatives. The diethyl ether extract showed moderate antitumor activity against HepG-2 liver cancer cells (IC₅₀ = 189.66 µg/ml), moderate antioxidant potential (IC₅₀ = 74.15 ± 3.27 mg/ml), and safe to moderate toxicity to normal WI-38 lung fibroblasts. These results underscore the high biomedical potential of S. microflavus BA2 as a promising source of natural agents for combating cancer and antibiotic resistance.