Incidência de fungos filamentosos e perfil de micobiota ocratoxigênica em grãos de café (Coffea arabica L.) processados pelo método via-seca em Minas Gerais

Abstract

Filamentous fungi when associated with coffee beans, can under certain physiological and environmental conditions cause damage that reflects on quality, producing unpleasant odors and flavors, in addition to favoring the production of mycotoxins. This work aimed to evaluate the diversity of filamentous fungi in coffee beans from five farms belonging to the state of Minas Gerais, from the South / Southwest and Vale do Mucuri mesoregions, in addition, we sought to select ochratoxigenic fungi and perform the quantification of production ochratoxin A by these. The identification was performed with the combination of different techniques such as: morphological characteristics, MALDI TOF MS and sequencing of the ITS and β-tubulin regions. The quantification of OTA of the isolates was performed by high performance liquid chromatography (HPLC). 389 filamentous fungi were isolated and the morphological identification revealed six genera of fungi: Aspergillus, Penicillium, Fusarium, Cladosporium cladosporioides complex, Alternaria and Eurotium. The contamination percentages varied from 7 to 100% between samples. In the DRBC medium, 226 filamentous fungi were isolated, equivalent to 58.09% of the total isolates. In the DG18 medium, 163 filamentous fungi, corresponding to 41.90% of the total of isolated fungi. Only 5 isolates were identified by MALDI TOF MS, 2 at the genus level (Penicillium sp) and 3 at the species level: A. niger. 24 representative isolates were identified by sequencing, 8 belonging to the genus Penicillium and 16 to Aspergillus, 23 were identified at the species level and 2 at the gender level. 41.88% of the isolates produced OTA. Aspergillus Section Nigri were more frequent, corresponding to 90.58% of the total of potentially ochratoxigenic isolates, however, only 39.5% produced OTA. The isolates of the Circumdati Section, corresponded to 10.42% of the potentially ochratoxigenic isolates and 67% of the isolates were OTA producers. The coffees from the municipalities of Itaipé and São Sebastião do Paraíso had a higher incidence of isolates producing OTA in high concentrations. The presence of toxigenic fungi does not necessarily indicate the presence of OTA, but it does indicate a potential risk.