Combinatorial activity of actinomycin D and X2 isolated from Streptomyces parvus 35M1 against Escherichia coli
Bildiriler > Tam Metin Bildiri
Yazarlar: O Can, M U Kurt, M Küçüksolak, A Uzel, E Bedir
Planta Medica, , , Uluslararası, Tam Metin Bildiri, Wos, cilt 92
Özet
The rise in antibiotic tolerance and resistance among Gram-negative bacteria and the limited development of new antimicrobial agents necessitate alternative treatment approaches such as combination therapy [ 1 ]. Streptomyces species are well-known natural product factories capable of synthesizing diverse bioactive compounds, including antibiotics, antifungals, and anticancer agents [[ 2 ] [ 3 ]]. Actinomycin derivatives, produced by Streptomyces sp., exhibit weak to moderate activity against Gram-negative pathogens [ 4 ]. To enhance their potency, this study aimed to evaluate the synergistic activity of actinomycin D and X2 with three clinically relevant antibiotics (polymyxin B, kanamycin, and nalidixic acid) against E. coli (ATCC 25922). The actinomycin derivatives used were isolated from marine-derived Streptomyces parvus 35M1. MIC studies indicated weak to moderate activity (203.91 and 100.83 μM) against E. coli . Later, a checkerboard assay was conducted to determine synergy, and inhibition data were analyzed using the Loewe and Bliss independence models via SynergyFinder. Strong synergy was found when the compounds were combined with polymyxin B (1/4 x MIC) and kanamycin (1/2 x MIC), decreasing the MIC value of actinomycins at least four-fold. Scanning electron microscopy revealed significant structural damage on E. coli , including abnormal elongation, ruptures, and dent formation. These findings suggest that actinomycin D and X2 can enhance the efficacy of nalidixic acid, polymyxin B, and kanamycin against E. coli , highlighting insights into novel strategies for combating Gram-negative bacteria. Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany