ENDOPHYTIC FUNGI ISOLATED FROM MEDICINAL TREE WARBURGIA UGANDENSIS COLLECTED FROM MOUNT KENYA FOREST
Endophytes are microorganisms living in cells and tissues of plants without causing diseases. Both the endophyte and the host plant experience a symbiotic mode of nutrition where by the endophytes get shelter and nourishment from the host plant and in return they increase the ability of the host plant to take up nutrients and to resist diseases. This study aimed at isolation of fungal endophytes from medicinal plant Warburgia ugandensis from Mt Kenya forest and determination of antimicrobial activity of the fungal extracts on Candida albicans, E coli and Staphylococcus aureus. Sterilized plant materials were incubated on tap water agar for six days at 26-27 ºC. Fungal positives were transferred to PDA plates followed by 4 days’ incubation at the same temperature. Colony purification gave pure cultures which were subjected to macroscopic, microscopic and sequencing methods of identification. Extraction of the bioactive compounds was done by sub-culturing the fungi in nutrient broth and use of organic solvent ethyl acetate. Preliminary phytochemical screening of the extracts was done. Antimicrobial activity of the extracts was determined using disk diffusion method according to CLSI protocols. Seventeen endophytic fungi were isolated and identified up to molecular level as; Nigrospora oryzae, Aspergillus flavus, Cladosporium sp. (two), Fusarium oxysporum, Phomopsis sp.(two), Colletotrichum acutatum, Altanaria sp. (two), Cochliobolus sativus, Bionectria ochroleuca, Phyllosticta gardeniicola, Guignardia mangiferae, Tricharina gilva, Diaporthe amygdale and Trichoderma harzianum. Phylogenetic tree of the isolates showed Aspergillus flavus strain Ya1 to be the evolutionary ancestor since its nucleotide sequence had not changed over time. Preliminary phytochemical screening of the fungal extracts showed absence of phenols and anthraquinones in all the endophytic fungal extracts; Presence of saponins, tannins, alkaloids, flavonoids, sterols and glycosides in most of the endophytic fungal extracts. Extracts of Phomopsis mali, Alternaria alternata and Fusarium oxysporum showed activity against Candida albicans, E. coli and Staphylococcus aureus with 8.7mm average diameter zone of inhibition; The rest of the extracts didn’t show any activity against the three test organisms. This study shows that fungal endophytes can be a potential source of metabolites which can be useful in pharmaceutical industry.