Abstract

MORENO PEREZ, P et al. Antimicrobial evaluation of extracts obtained from tropical micromycetes against phytopathogens. Phyton (B. Aires) [online]. 2016, vol.85, n.1, pp.7-14. ISSN 1851-5657.

Nowadays, it is highly necessary to fnd more and safer agrochemicals. In this sense, micromycetes are an important source of natural products which could be used to control plant diseases. Therefore with the aims to contribute in this searching of natural products with antimicrobial applications, a total of 49 fungal strains were isolated from the Yucatan Peninsula. These fungi were cultured in fermented rice, their respective organic extracts macerated in ethyl acetate (EAE) and methanol (ME) were obtained and tested against five fungal pathogens of agricultural importance. These included Alternaria chrysanthemi, Colletotrichum gloeosporioides, Mycosphaerella fijiensis, and the bacteria Erwinia carotovora and Xanthomonas campestris using microdilution assays. The 69% of fungal extracts showed antifungal or antibacterial (2000 and 200 µg/mL, respectively) against at least one of the tested target. Strains Penicillium sp. OSE-61, Fusarium sp. OH2-30, Hypocrea lixii OSN-37 and Rhizoctonia solani OSE-73 showed activity against at least three of the five study pathogens. The most active EAE were partitioned, and its low (A), medium (B) polarity and precipitated (C) were obtained and assessed. The fraction A from Fusarium KS-15 displayed the lowest Minimum Inhibitory Concentration (MIC ≤25 µg/mL) and bactericide effect on X. campestris; fraction B of Penicillium sp. OSE-61 was relatively greater than the previous on A. chrysanthemi (MIC ≤500 µg/mL). Last fraction also exhibited good inhibitory effect on C. gloeosporioides. Finally, fraction B of H. lixii OSN-37 displayed promissory antifungal effect on C. gloeosporioides y M. fijiensis (MIC = 1000 µg/mL). This research contributes to enrich the limited knowledge on the biological activity of native anamorphic fungi of the sinkholes of Yucatan and its potential use in biotechnological applications in agriculture.

Keywords : Bioassays; Fungal extracts; Fusarium; Hypocrea; Microfungi; Penicillium; Sinkholes.

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