Antibacterial activity of endophytic fungi from the medicinal plant Uncaria tomentosa (Willd.) DC

This study was designed to determine the diversity and antibacterial activity of endophytic fungi isolated from Uncaria tomentosa. Leaf and stem were disinfected superficially and inoculated in PDA and SDA medium, with and without plant extract and incubated at 18 and 28°C for isolation of endophytic fungi. Endophytic fungi were inoculated in BD medium and the metabolites extracted with ethyl acetate. Endophytic fungi extracts were tested for antibacterial activity by the disk diffusion test.One hundred and seventy endophytic fungi were isolated and identified as Aspergillus, Asterosporium,Aureobasidium, Botrytis, Colletotrichum, Curvularia, Didymostilbe, Fusarium, Guignardia, Nigrospora,Penicillium, Pestalotiopsis, Phomopsis, and sterile mycelium. Staphylococcus aureus was the most resistant bacterium, with only two fungal extracts inhibiting its growth, while the most sensitive was Escherichia coli, with 23 extracts inhibiting its growth. Five extracts inhibited Enterococcus faecalis and four Klebsiella pneumoniae. No fungal extract was able to inhibit the four tested bacteria. Extracts from endophytic fungi isolated from U. tomentosa showed in vitro antibacterial activity against grampositive and gram-negative bacteria.