Chemical and biological investigation of rhizospheric Streptomyces from Ebenus sibthorpii

The rise of multi-drug resistant pathogens (MDR) underscores the urgent need for developing new antibiotics. Natural products, particularly bacteria-derived metabolites, are a promising source of bioactive compounds with significant antimicrobial potential. Plant-associated microbiomes, especially in the rhizosphere, are integral to plant protection and growth, primarily through antibiotic production. Among these, Streptomyces species, abundant in rhizospheres, are renowned for their robust antimicrobial and anti-fungal compound synthesis [ 1 ]. This research aimed to isolate and evaluate Streptomyces strains from the rhizosphere of the Ebenus sibthorpii plant as potential sources of antimicrobial metabolites. Streptomyces scopiformis was identified through molecular techniques, selected based on significant antibiotic and antifungal activity against indicator organisms. Laboratory and pilot-scale cultures of this strain were undertaken, and extensive chemical analysis of both culture micelles and nutrient materials was performed using LC-HRMS/MS, identifying a total of 100 compounds. The centrifugal partition extraction technique was crucially employed to efficiently separate and fractionate nutrient substances, demonstrating excellent separation capability and significant time efficiency. Additionally, acid precipitation and sedimentation methods with water and acetonitrile facilitated further fractionation. Preparative thin-layer chromatography was subsequently utilized for additional purification and identification. Bioactivity assays against Candida albicans and Staphylococcus aureus indicated that specific nutrient fractions exhibited notable antimicrobial activities. Overall, this study effectively validated the methodology and experimental protocols developed, establishing a robust framework for exploring and characterizing the antimicrobial chemical content of Streptomyces -derived metabolites from rhizosphere microbiomes. Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany