Antibacterial potential of fungal endophytes isolated from Boerhaavia diffusa L.

ABSTRACT

Boerhaavia diffusa L. is widely used for its ethno-medicinal properties. The present study assessed the antibacterial activity of endophytic fungi harbored in this plant. The endophytic fungi isolated belonged to various genera like Aspergillus, Cladosporium, Colletotrichum, Curvularia, Fusarium, Pestalotiopsis and Zygorhynchus and the overall colonization frequency of endophytic fungi was found to be 24%. Among the isolated fungi Aspergillus fumigatus, Cladosporium sphaerospermum, Fusarium sp. and Zygorhynchus sp. showed antibacterial activity in preliminary screening against one or all the test bacteria. Further, after fermentation, the ethyl acetate extracts of the selected endophytic fungi displayed variable antibacterial activity with maximum 54.75 mm and a minimum 27.50 mm zone of inhibition against test bacteria in disc diffusion assay. The lowest minimum inhibitory concentration (MIC) was 0.156 mg ml-1 in the broth dilution assay against a B. subtilis, S. typhi and S. aureus, while it was 0.312 mg ml-1 against E. coli which was offered by the ethyl acetate extracts of A. fumigatus.