Production of Agaricus bisporus on substrates pre-colonized by Scytalidium thermophilum and supplemented at casing with protein-rich supplements

The objective of this study was to evaluate performance of Agaricus bisporus (Ab) on substrates pre-colonized by Scytalidiumthermophilum (St), a thermophilic fungus known to enhance yields of Ab and increase selectivity of the substrate. The radial extension rate (RER) of the mycelium of three strains of St and their influence on the growth of a brown strain of Ab were evaluated. We also determined the time required for colonization of pangola grass by St in a compost pile and the influence of three protein-rich supplements on yield of Ab on pangola grass (Digitaria decumbens) colonized by St. RER of St ranged from 10.1 mm/d on grass to 18.9 mm/d on potato dextrose yeast extract agar, with significant differences among substrates and among strains. Ab grew faster on substrate colonized for 1, 2, or 3 days by St (RER of 3.31, 3.29, 3.23 mm/d, respectively) compared to non-colonized substrate (1.85 mm/d). Ab was cultivated on substrate samples selected daily from the St-inoculated pile, with biological efficiencies (BE) ranging from 4% (day 0) to 73.9% (day 2). Protein-rich supplements (soybean, black beans and cowpeas) added at casing significantly stimulated mushroom yield on St-colonized substrate compared to the non-supplemented control. BE varied from 26.1% on substrate non-supplemented to 73.1% on compost supplemented with ground soybean. There were no significant differences in mushroom yield observed among supplements evaluated.