Agaricus bisporus and related Agaricus species on lignocellulose: production of manganese peroxidase and multicopper oxidases.

Biotechnological, microbiological, and genetic studies of Agaricus species other than A. bisporus, the white button mushroom, have been limited so far. To expand the knowledge in the genus Agaricus, six novel wild-type isolates of Agaricus spp. were studied on their nutritional demands for enzyme production and mycelial growth. All the selected Agaricus species produced extracellular manganese peroxidase (MnP) and laccase activities in semi-solid rye bran cultures. Moderate MnP activities were measured for A. bisporus, A. bernardii and A. campestris. The highest laccase activities were obtained for A. bisporus and A. campestris. On soy medium, the highest mycelial tyrosinase activity was determined for A. bernardii. For A. bisporus, addition of copper caused no increase in laccase or tyrosinase activities on soy or malt extract media. Hyphal growth rate of the isolates was studied on lignocellulose amended agar plates. Fastest growth was obtained for A. bisporus on wheat bran and birch leaf litter agar. Except for A. bernardii, hyphal growth rates correlated well with MnP and laccase production levels between Agaricus species. Molecular taxonomy of the novel Agaricus spp. positioned them to distinct phylogenetic clusters with species-level identity. In conclusion, our data point to the importance of both MnP and multicopper enzymes in Agaricus spp. while growing on lignocelluloses.