Endophytic Fungi from Uruguayan Native Myrtaceae: Enzymes Production, Antimicrobial and Phytotoxic Activity

In recent years fungal endophytes occurring in native Myrtaceae from Uruguay have been studied. Fungal associations with the host, such as saprotrophs, latent plant pathogens or symbiotic, are related with enzymes and secondary metabolites production. Therefore, a main goal of this work was to evaluate the ability of endophytic fungi isolated from Myrcianthes cisplatensis, Myrrhinium atropurpureum and Eugenia uruguayensis to produce hydrolytic and oxidative extracellular enzymes and bioactive metabolites with antimicrobial activity or phytotoxic properties. Enzymes production were evaluated by plate assay and metabolites were extracted with organic solvents. For detecting phytotoxicity, fungal extract were injected on fresh leaves of E. uruguayensis. Antimicrobial activity was evaluated by antibiogram technique and growth inhibition assessed by halo. Cladosporium sphaerospermum, Xylaria acuta and Amphisphariaceae 143 that showed the highest enzymatic activity probably degrading plant debris when they arrive to soil having saprotrophic life style. The enthomopathogenic fungus Metarhizium anisopliae producing proteases and chitinases is active pathogen of several insect species. In addition, Nigrospora spherica and Xylaria sp. produced necrotic spots on Myrtaceae leaves evidencing phytotoxic activity. The antifungal activity showed by some endophytic species evidenced the ability to limit the development of microorganism populations. Lophiostoma sp. 246 was the most active strain against Staphyloccocus aureus and Candida albicans and Preussia. africana evidenced a good antimicrobial activity against Xanthomonas campestris. Native Myrtaceae seems to be a good source of fungal endophytes for producing enzymes related with decomposition process and a promising source of bioactive metabolites with antimicrobial and fitotoxigenic activities. In addition, the new strain of M. anisopliaes could be a promising bioinsecticide.