The demand for novel metabolites that can be used to combat antibiotic resistance and plant diseases is increasing in recent years. This study examined mangrove-associated endophytic fungi as a potential source of novel antibacterial activity given that they thrive in complex and dynamically challenging habitats making them a valuable source of bioactive compounds. In this study, a total of twenty-eight (28) endophytic fungi were isolated from the foliar tissues of Rhizophora stylosa Griff. originating from Bayug Island, Iligan City, Lanao del Norte, Mindanao, Philippines. The genera of the isolates were identified through culture morphology and microscopic characterizations. The isolates were screened for antibacterial activity by disc diffusion assay using Escherichia coli BIOTECH 1634, Staphylococcus aureus BIOTECH 1582, and Xanthomonas sp. isolated from rice leaf and capsicum leaf tissues. Results demonstrated five (5) isolates showing antibacterial activity against E. coli and S. aureus including Aspergillus sp. (ML9C1B), Cladosporium sp. (ML9C1A), Sclerotinia sp. (ML2C1B), Rhizoctonia sp. (ML10C4A) and ML2C3D (unidentified) . Meanwhile, only one isolate, Sclerotinia sp. (ML2C1B), exhibited antibacterial activity against Xanthomonas sp. from rice leaf. None of the isolates were found effective against Xanthomonas sp. from capsicum leaf. These findings show that mangrove-associated fungi are potential sources for bioactivity combating bacterial pathogens and may be a source of metabolites effective against antibiotic-resistant pathogens thus requiring further studies.
