Lignocellulosic supplementation of the culture medium for mycelial development and production of phenoloxidase enzymes from Amazonian strains of gasteroid fungi (Basidiomycota)

Abstract

Strains of gasteroid fungi are capable of oxidizing phenolic components and producing enzymes of great commercial value. However, the difficulty in producing biomass and, consequently, the low levels of expression of enzymes produced by these fungi hinder the advancement of biotechnological studies. A possible alternative may be supplementing the culture medium with lignocellulosic substrates, as observed in the cultivation of edible mushrooms, for example. Thus, the objective of this study was to analyze the effect of supplementing a potato-based culture medium with different concentrations of wheat and rice bran on mycelial development and the production of phenoloxidase enzymes of Amazonian strains of Cyathus and Geastrum. The basidiomas were collected in the Amazon of Pará, and the strains were obtained from mycelial isolation on Potato Dextrose Agar (PDA) medium. The strains were inoculated in semi-solid and liquid potato-based medium containing 10% and 20% rice bran and 10% and 20% wheat bran. For a period of 20 days, mycelial growth was observed in solid form, and for 40 days, the development of the strains in liquid medium was monitored, all incubated at 25°C in the dark. Growth and production of fresh and dry biomass were measured, as well as the production of phenoloxidase, arising from growth in liquid medium. Supplementation using 10% wheat bran was the most promising for the radial growth of four of the six species tested (C. limbatus, G. hirsutum, G. echinulatum, and G. schweinitzii), in addition to being the best treatment for the production of biomass and phenoloxidase enzymes for all species. Considering that wheat bran is easily accessible, this study stimulates basic science, especially in the Amazon, where Funga is still underestimated in terms of diversity and biotechnological potential.