Diversity and association of filamentous fungi in coffee beans under organic and conventional cultivation

Brazil is a country with great biodiversity; however, knowledge of this microbiological wealth is currently insufficient for its utilization in a sustainable manner. Agricultural expansion represents one of the largest current dangers to biodiversity and threatens to cause the extinction of a variety of species. This study therefore aimed to isolate and identify the species of fungi present in coffee beans cultivated in organic and conventional systems. Eighteen (18) samples of coffee beans from southern Minas Gerais were analyzed, and 346 fungal isolates were obtained from the analyzed coffee beans. These isolates belonged to 32 species in the following 14 genera: Aspergillus, Penicillium, Fusarium, Cladosporium, Mucor, Rhizopus, Trichoderma, Epicoccum, Phoma, Bipolaris, Glomerella, Colletotrichum, Alternaria and Gliocladium. Organic coffee bean samples exhibited the highest indices of fungal diversity. Two species identified in this study, Aspergillus flavus and Aspergillus ochraceus, are extremely important for their toxigenic characteristics. We utilized simple correspondence analysis to evaluate the interaction of the identified fungi with the toxigenic species. An association of toxigenic fungi with other fungi is important because some microorganisms can degrade mycotoxins. In the organic coffee beans, A. flavus was associated with Cladosporium cladosporioides, A. ochraceus, and Penicillium brevicompactum. In contrast, in the conventional coffee beans, A. ochraceus was only associated with C. cladosporioides. These results demonstrate that greater fungal diversity exists in organic coffee beans.