Isolation and identification of a novel phthalate derivative from Streptomyces sp. grown on peanut shells with antimicrobial activity

Antimicrobial resistance to pathogens is the cause of several million deaths globally. Therefore, the aim of the current study is to identify and isolate a new antimicrobial agent from Streptomyces sp. effective against several pathogenic microbes, including multidrug resistant (MDR) pathogens, using agriculture waste. Streptomyces isolate strain from the Egyptian soil was isolated, identified and grown on a local agricultural waste. The antimicrobial activity of the fermentation medium was tested against several pathogens using the well diffusion method. The most suitable fermentation and environmental factors for the maximum production of the antimicrobial bioactive compound was determined. Finally, the bioactive compound was purified, and characterized using several chromatographic and instrumental analyses. We identified Streptomyces bingchenggensis FHM200 isolate strain grown on peanut shells wastes. The maximum antimicrobial activity was attained by incubation with 2% (v/v) of the isolated strain (10⁵ spores / mL) at temperature range of 28–30℃ and pH range of 7.5 to 8 for 5 days, supplemented with potassium nitrate 0.2% (w/v) and dipotassium hydrogen phosphate (1 g/L). Finally, we managed to isolate and purify a novel bioactive compound; hexyl (2-hydroxyhexyl) phthalate, that possessed a promising antimicrobial activity against all tested pathogens with MIC of 70 µg/mL for Bacillus cereus ATCC 33018, 150 µg/mL for Aspergillus niger NRRL 326, and for MDR pathogens; 2500 µg/mL for methicillin resistance Staphylococcus aureus (MRSA) ATCC 43300, and 3000 µg/mL for both Escherichia coli 797, and Candida albicans 210. We concluded that hexyl (2-hydroxyhexyl) phthalate, isolated from Streptomyces bingchenggensis FHM200, possesses promising antimicrobial activity.