Abstract

A total of 72 endophytic fungal isolates including 48 from leaves, 14 from stems, 6 from roots and 4 from flowers were obtained from medicinal herb, Orthosiphon stamineus Benth by adding host plant materials in isolation medium. Sixty-six (92%) of the 72 isolates exhibited significant inhibitory activity on at least one of the test microorganism. Methanolic extract, prepared from the fungal biomass, exhibited better antimicrobial activity compared with ethyl acetate extract from fermentative broth and volatile antimicrobial compounds. The antimicrobial activity of the isolates was affected by the culture medium. A better antimicrobial activity was observed in the yeast extract sucrose broth compared with malt extact broth. Significant improvements in the antimicrobial activity of the crude extract and volatile fungal metabolites were observed after addition of water extract of the host plant in the culture medium.

Key words: Orthosiphon stamineus Benth, endophytic fungi, antimicrobial actvity, host plant extract.