Evaluation of antimicrobial activity of endophytic fungi from Camptotheca acuminata (Nyssaceae)

Agricultural research of plant-derived endophytic fungi has grown in recent decades. We isolated 26 endophytic fungi from the leaves, stems and fruits of the tree of life, Camptotheca acuminata, and tested them for antimicrobial activities based on growth inhibition measurements in a modified agar diffusion method. Fermentation broths from most of the isolates exhibited antifungal activity and 50% exhibited antibacterial activity; some of them also exhibited strong broad-spectrum antimicrobial activity. The strongest antimicrobial activity was exhibited by strains XSY10 and XSY15 against Rhizoctonia solani and Fusarium oxysporum f. sp. vasinfectum, with 75% and 67% inhibition, respectively. Strain XSJ01 gave strong activity against pathogenic bacteria, with inhibition zones more than 20 mm in diameter. The isolates were identified by molecular methods as belonging to nine taxa: Nigrospora, Diaporthe, Alternaria, Colletotrichum, Pestalotiopsis, Sordariomycete, Guignardiai, Penicillium, and Zythia. Based on these results, we conclude that the endophytic fungi of C. acuminata are promising sources of novel bioactive compounds.