Biodiversity of endophytic fungi in different leaf ages of Calotropis procera and their antimicrobial activity

Calotropis procera has many important medicinal properties with proven pharmacological potential. Some of these properties may be mediated by its fungal endophytes. This study analyzed, for the first time, the community of endophytic fungi of C. procera outside its region of origin. A total of 156 fungal isolates distributed across 19 taxa were obtained from 468 fragments of C. procera leaves at different stages of maturation. The rate of endophyte colonization increased with the leaf age/development. The dominant species of endophytic fungi of C. procera introduced in Northeast Brazil were different from those found in studies on the same species and other species of the same genus in native regions. The dominant endophyte was Phaeoramularia calotropidis (63.5 %), followed by Guignardia bidwellii (21.1 %). Six isolates of endophytic fungi showed antimicrobial activity against human pathogenic micro-organisms and one plant pathogenic fungus. The antibacterial activity was more intense than the antifungal activity. The endophytic Curvularia pallescens (URM 6048) stood out inhibited Gram-positive bacteria, Staphylococcus aureus, Streptococcus pyogenes, the plant pathogenic fungus Colletotrichum dematium. Ecological and biotechnological aspects of endophytic mycota are discussed.