Antagonistic activity and chitinolytic potential of endophytic fungi recovered from cacti growing in the Brazilian tropical dry forest

Abstract

This study aimed to evaluate the antagonistic activity and chitinolytic potential of 20 species of fungal endophytes isolated from Cactaceae species and deposited at the URM culture collection in Brazil against nine strains of phytopathogenic fungi isolated from the forage cactus Nopalea cochenillifera. Phytopathogenic fungi were obtained from diseased tissues of N. cochenillifera and identified through analyses of morphology and DNA sequences of different genes (ITS rDNA, RPB2, and TEF1). The antagonistic potentials of these endophytes were analysed in terms of inhibition, parasitism and competition, and the enzyme activity by assay in submerged fermentation using colloidal chitin as a carbon source. Nine phytopathogenic fungi were isolated and identified as belonging to Alternaria, Curvularia, Fusarium, Neoscytalidium, and Neurospora. Antagonism by inhibition was the most significant category, with 17 endophytic species having inhibitory potential. Aspergillus tamarii URM 7505 and Penicillium griseofulvum URM 6846 inhibited all tested pathogenic fungi. Although all 20 endophytic fungal species effectively produced chitinase (0.20–5.36 U/ml), the highest production level was observed for Aspergillus parasiticus URM 6868 (5.36 U/ml).