Desenvolvendo micocompósitos a partir de aditivos e rejeitos minerais, resíduos agrícolas e isolados da família Ganodermataceae (Fungi, Basidiomycota) de origem brasileira.

Abstract

Recent advances on the development of mycocomposites have emerged given the current sustainability and environment issues. These materials are based on the aggregative characteristics of the hyphal systems of fungi, which grow on the substrate, generating light and resistant materials, characteristics that enable their use in several industrial fields, with potential to replace polystyrene, leather, paper, among others. Variables in the development of these materials, such as the selection of fungal isolate and substrates, can influence the characteristics of the final product. The aims of this work were to evaluate the best combination of agro-industrial residues (i) those originated from the sisal shredding process (Agave sisalana), (ii) those derived from the fiber industrialization, and (iii) the residue from oil palm cultivation with the use of mineral additives, such as mining waste, for the growth of several fungal isolates: Ganoderma lucidum CCMB 601, Ganoderma sp. DHCR 356, Ganoderma sp. DHCR 379, and Ganoderma australe CCMB 456, focusing on the development of mycocomposites that can be potentially used in the civil construction field. When using mineral additives individually, all additives positively influenced the fungal growth, but phyllite mineral showed a greater influence on the growth of fungi. Regarding its composition, phyllite stands out for its high composition of magnesium oxide and low composition of aluminum oxide when compared to other mineral residues. Due to the significance of all additives, the low economic value (or non-existent), and environmental appeal, phyllite and mining waste were selected for further tests. Regarding the mechanical behavior, in the thermogravimetry, bending, and compression tests we verified that the mineral additives have an effect on the mechanical behavior of the material, functioning as modulators. Thus, the use of the additives, both phyllite and mining waste, directly increased the density of materials, increased the compressive strength, and decreased the flexural strength of the material. The thermogravimetric analysis showed that the phyllite additive has a protective effect on the burning of the material, delaying the loss of mass while temperature increases, which is relevant for materials in which the ignition resistance is required; however more specific tests must be performed. Moreover, micro and macroscopic analyzes demonstrated that neither phyllite or mining waste caused higher mycelium aggregation, as expected. We also established here a promising alternative technique for qualitative evaluation of mycocomposites: fluorescence microscopy using calcofluor white, a non-specific fluorochrome that binds to cellulose and chitin in cell walls. For qualitatively determine the degree of aggregation of the material and the affinity of the fungi for the substrate used as a matrix, the calcofluor white stain is more viable (fast preparation and evaluation) and cheaper compared to the scanning microscope. The G. lucidum CCMB601 isolate was used for mechanical tests due to its rapid growth and greater mycelial density, but the Ganoderma sp. DHCR 379 isolate also had similar behavior, and can be a promising choice for further tests.