Antibacterial activity of endophytic fungi isolated from Croton lechleri (Euphorbiaceae)

Croton lechleri is a native species from the Amazon and used with relative frequency in folk medicine in Brazil and other countries. Diversity and antibacterial activity of endophytic fungi associated with this plant were studied here. Samples of leaves and stems were used and 575 endophytic fungi were isolated (307 from leaves and 268 from stems), comprising 284 morphotypes distributed in 13 genera and unknown. The most frequently isolated genera were Phomopsis (30.78%), Penicillium (21.57%) and Pestalotiopsis (16.70%). Diversity and richness of species were higher in leaf tissues. Fifty-five fungi presented antibacterial activity. The fungi with the highest activity were Phomopsis (6.34%), Penicillium (3.17%), and those unknown (5.28%). Penicillium sp. 9 showed the highest antibacterial activity against Enterococcus faecalis and Phomopsis sp. 8 and Phomopsis sp. 9 against Streptococcus pneumoniae and Staphylococcus aureus. Curvularia sp. 1 and a fungus that could not be identified (Unknown sp. 9), showed the highest antibacterial activity against Klebsiella pneumoniae and Escherichia coli, respectively. Only two fungi (Penicillium sp. 9 and Curvularia sp. 1) inhibited the five tested bacteria. Endophytic fungi of C. lechleri harbor a great diversity of endophytic fungi, which have the potential for producing antibacterial compounds. Key words: Dragon’s blood, antibacterial agent, endophytic fungi, microbial interaction.