The rate of colonization of the compost by A. bisporus is
stimulated by the microbial biomass present in compost at
spawning. The most abundant fungus present after composting, Scytalidium thermophilum, was found to have a
growth promoting effect on mycelial growth of A. bisporus
upon addition to sterilized compost (Straatsma et al., 1989;
1994b). The same stimulating effect, but now measured as a
significant increase in mushroom yields, was found when this
thermophilic fungus was inoculated into compost that was
pasteurized at some point in the composting process just
before S. thermophilum normally starts to accumulate
(Straatsma et al., 1994a).