Antimicrobial potential and cytotoxicity of endophytic fungi crude extracts from Ricinus communis of Tanzania

Abstract. Shemnkande NS, Lyantagaye SL, Mpenda FN. 2023. Antimicrobial potential and cytotoxicity of endophytic fungi crude extracts from Ricinus communis of Tanzania. Asian J Trop Biotechnol 20: 69-78. The study aimed to assess the antimicrobial potential and cytotoxicity of crude extracts from endophytic fungi found in Ricinus communis L. from Tanzania. The researchers isolated and identified fifty-one fungi species from the leaves and roots of R. communis. The isolates were morphologically characterized, considering color, size, shape, elevation, margin, and density parameters. The isolates were further analyzed using Sanger sequencing and bioinformatics tools to determine their phylogenetic relationships and identify the isolates. Two techniques were deployed to evaluate the antimicrobial potential: disc diffusion and microdilution. The disc diffusion method measured the inhibition zones formed by the fungi extracts against selected bacterial strains (Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. In comparison, the microdilution technique determined the crude extracts' Minimum Inhibitory Concentrations (MIC) against the bacterial strains. Cytotoxicity of the crude extracts was evaluated using the brine shrimp lethality assay; Brine shrimp larvae were exposed to the extracts to evaluate their potential toxicity. The study successfully isolated 51 fungi species from R. communis and observed significant morphological variation. Four endophytic fungi (Penicillium menonorum, Curvularia verruculosa, Aspergillus niger and Aspergillus aculeatinus) exhibited potent antibacterial activity against B. subtilis, E. coli, P. aeruginosa, and S. aureus, with low minimum inhibitory concentrations (3.125 µg/mL to 0.098 µg/mL). Cytotoxicity tests on brine shrimp larvae indicated the crude extracts' non-toxicity, suggesting their potential as safe therapeutic agents. The findings suggest that endophytic fungi from R. communis possess potential therapeutic applications against drug-resistant pathogens, warranting further investigation of their bioactive compounds and broader biotechnological uses.