Abstract Agaricus subrufescens is a basidiomycete which is studied because of its medicinal and gastronomic importance; however, less attention has been paid to its preservation. This study aimed to evaluate the effect of sucrose addition to substrate and cryotube on the viability of Agaricus subrufescens cryopreserved at -20 °C and at -75 °C for one and two years. Zero, 10% or 20% sucrose was added to potato dextrose agar or wheat grain. The mycelia were cryopreserved in the absence of cryoprotectant or with sucrose solutions at 15%, 30% or 45%. After one or two years at -75 °C or at -20 °C, mycelia were thawed and evaluated about viability, initial time of growth, colony diameter and genomic stability. Cryopreservation at -20 °C is not effective to keep mycelial viability of this fungus. Cryopreservation at -75 °C is effective when sucrose is used in substrates and/or cryotubes. Without sucrose, cryopreservation at -75 °C is effective only when wheat grains are used. Physiological characteristic as mycelial colony diameter is negatively affected when potato dextrose agar is used and unaffected when wheat grain is used after two-year cryopreservation at -75 °C. The fungus genome does not show alteration after two-year cryopreservation at -75 °C.

As técnicas de cultivo do Agaricus brasiliensis (método de compostagem) e formulação de substrato são as mesmas utilizadas para o Agaricus bisporus. A maioria das relações carbono/nitrogênio (C/N) relatadas para A . brasiliensis são similares às usadas para A. bisporus no método de compostagem. Há poucos estudos sobre a variação da relação C/N para A. brasilienses para o método axênico. O objetivo deste trabalho foi verificar o efeito de diferentes relações C/N no crescimento micelial de Agaricus brasiliensis utilizando subprodutos regionais como substrato pelo método axênico. As relações C/N no substrato (misturas de fibra de soja e de mandioca) estudadas variaram de 11 a 248 com consequentes concentrações de nitrogênio de 4,25 a 0,20%, respectivamente. Concluiu-se que os substratos somente com fibra de soja propiciam maior crescimento micelial que qualquer mistura com fibra de mandioca; o crescimento micelial é maior no substrato com relação C/N de 11 (N = 4,25%), intermediário na faixa de relação C/N entre 15 e 50 (N = 3,31 e 0,98%) e menor na relação C/N de 100 ou superior (N < 0,50%).

Cultivation techniques for Agaricus brasiliensis (composting method) and substratum formulations are the same ones used for Agaricus bisporus. Most of the carbon-to-nitrogen (C:N) ratios reported for A. brasiliensis are similar to those used for A. bisporus on the composting method and there are few studies about the variation of C:N ratios for A. brasilienses on the axenic method. The objective of this study was to verify the mycelial growth of A . brasiliensis on different C:N ratios using regional by-products as substrate formulation on the axenic method. Studied C:N ratios of substrate (mixture of soybean and cassava fibers) ranged from 11:1 to 248:1, with nitrogen content ranging from 4.25 to 0.20%, respectively. It was concluded that substrate with only soybean fiber generates higher mycelial growth than any formulation with cassava fiber; the highest mycelial growth on substrate is with C:N ratio of 11:1 (N = 4.25%); the intermediate growth is with C:N ratio range from 15:1 to 50:1 (N from 3.31 to 0.98%); and the lowest growth is with C:N ratio of 100:1 or higher (N < 0.50%).