Biosynthetic potential of endophytic fungi associated with breadfruit (Artocarpus communis forst.) for antimicrobial agent production

Abstract

The rising incidence of antibiotic resistance in pathogenic bacteria necessitates the exploration of endophytic fungi as alternative sources of novel antimicrobial compounds. This study aimed to isolate, characterize, and evaluate the antimicrobial potential of endophytic fungi derived from the leaves and stems of breadfruit (Artocarpus communis Forst) against Staphylococcus aureus, Escherichia coli, and Candida albicans. Isolation was conducted using surface sterilization and direct plating methods on Potato Dextrose Agar (PDA). Fungal isolates were characterized macroscopically and microscopically. Antimicrobial potential was assessed in two stages: preliminary screening using the dual culture antagonism method, followed by confirmation testing of secondary metabolites produced via liquid fermentation in Potato Dextrose Broth (PDB) using the agar well diffusion method. Eight pure isolates were successfully obtained: three from leaves and five from stems. Preliminary screening indicated that stem-derived isolates exhibited superior antimicrobial activity compared to leaf-derived isolates. Secondary metabolite screening revealed that isolate B1a-Ir effectively inhibited S. aureus with an inhibition zone of 9.19±0.17 mm, surpassing the positive control (chloramphenicol). Furthermore, isolates B2a-Ir and B3b-Ir exhibited strong antifungal activity against C. albicans with inhibition zones of 13.09±0.49 mm and 13.93±0.17 mm, respectively, surpassing the positive control (ketoconazole). This study highlights that endophytic fungi from breadfruit stems are promising sources of bioactive compounds for future antimicrobial therapy development, particularly against S. aureus and C. albicans.