Characterization of Promising Antifungal Bioactive Compounds from Endophytic Actinobacterium, Streptomyces rochei OM182844

This study evaluated the activity of a newly identified endophytic actinobacterium strain Streptomyces rochei OM182844 as an antifungal agent against soil-borne pathogenic fungi, Fusarium oxysporum f.sp < em>. cucumerinum, Sclerotinia rolfsii, and Pythium aphanidermatum. The antifungal activity was performed using Strep. rochei culture and its crude culture filtrate (CCF), and they showed superiority in the antagonistic activity towards the three tested pathogens as inhibition of growth on plates and reduction of mycelial growth weight in broth. Strep. rochei was a high producer of cell-wall degrading enzymes (chitinases and cellulases) as a tool used to degrade pathogenic fungal-cell walls. In addition, the released volatile organic compounds (VOCs) were submitted for GC/MS analysis; it showed that the most abundant compounds were Hexadecanoic acid, trimethylsilyl ester (CAS) followed by iridomyrmecin which have antifungal activities. Hence, the success of our idea of using actinobacteria isolated from healthy plants as a biocontrol agent is a promising point for much research towards the production of unconventional and environmentally safe biocides.