Agro-waste valorization of sweet potato peel waste for production and characterization of antibacterial bioactive metabolites from Streptomyces diastaticus

Abstract

The emergence of antimicrobial resistance (AMR) in clinical, environmental, and agricultural settings is a major global concern, necessitating sustainable and environmentally friendly solutions. Simultaneously, environmental pollution resulting from the improper disposal of agro-wastes poses an additional challenge requiring effective waste management strategies. A soil isolate identified as Streptomyces diastaticus (GenBank accession number PQ469050.1) was utilized for the production of bioactive metabolites. Apple pomace, sweet potato peel, and rice husk were evaluated as agro-waste substrates, and sweet potato peel waste was selected on the basis of the highest crude metabolite yield obtained after solvent extraction. Fermentation was carried out using the selected substrate, and the resulting fermentation broth was extracted with ethyl acetate. The crude extract was subsequently subjected to partial purification by column chromatography, followed by characterization using Fourier transform infrared spectroscopy, Gas Chromatography–Mass Spectrometry, and ¹H Nuclear Magnetic Resonance. The antibacterial activity of the partially purified bioactive fraction was evaluated against selected human pathogens: Escherichia coli (ATCC 4157), Klebsiella pneumoniae (ATCC 13882), and Shigella flexneri (ATCC 9199). The highest antibacterial activity was observed against K. pneumoniae, with a zone of inhibition of 17 mm. These findings demonstrate that sweet potato peel waste can serve as an effective and low-cost substrate for the production of bioactive metabolites by S. diastaticus, contributing to agro-waste valorization and providing a basis for the development of potential antimicrobial agents.