Resíduo de erva-mate - sucessão fúngica e utilização como substrato na produção do cogumelo comestível pleurotus ostreatoroseu

Abstract

The production of organic waste has increased considerably in recent years and the way it is disposed of has been causing damage to the population and the environment, requiring research to find alternative uses for it. In Rio Grande do Sul, a large part of the organic domestic waste derives from the use of yerba mate (Ilex paraguariensis A. St.-Hil), consumed by the population in the form of mate, due to cultural habits. This study aimed to evaluate the fungi associated with the decomposition of yerba mate and to propose a methodology for home cultivation of the edible mushroom Pleurotus ostreatoroseus using yerba mate as substrate. To evaluate the fungi associated with decomposition, yerba mate discarded after use in mate tea was collected by five consumers for a period of thirty days during the autumn, winter, and spring seasons of 2020, totaling 450 samples, which underwent a two-month maturation period for proliferation of the associated fungi (the summer period was not included due to the pandemic modified the research schedule). For the cultivation methodology of Pleurotus ostreatoroseus in yerba mate, three substrate compositions based on yerba mate were prepared: 1) partially decomposed yerba mate; 2) fresh yerba mate; 3) fresh yerba mate added to eucalyptus sawdust in three different concentrations (30%; 50%; 70%), packed in canning jars and bamboo stalks (Bambusa tuloides). As for the evaluation of the fungi associated with decomposition, 22 genera of fungi associated with the residue were found, of which the Zygomycota (Rhizopus and Mucor) stand out in the microflora of initial colonization, having exclusive growth in the first 19 days. After this period, the Deuteromycota (mainly Aspergillus) and Oomycota (Pythium) fungi develop with more vigor, supplanting Rhizopus e Mucor. The species of Curvularia, Fusarium, Verticillium, and Pythium are phytopathogens and end up having their source of inoculum increased with the irregular disposal of this waste. The results regarding the cultivation in pure discarded yerba mate, both partially decomposed and fresh, proved to be unfeasible to cultivation, contrary to what is reported in the literature, with colonization of the substrate by the mycelium, but without production of basidiomes. In the cultivation with addition of eucalyptus sawdust, all concentrations showed formation of primordia, being the concentration with 70% sawdust the one that first fructified (9 days) and that presented the largest basidiomes (5 cm). Thus, the present work contributes to the knowledge of fungi associated with yerba mate waste and also proposes a way to reuse this waste in the production of the edible mushroom Pleurotus ostreatoroseus.