Volume 13 Part 1 Article 30: Mushroom compost microbial biomass: A review

Volume 13 Part 1 Article 30
Year 1991
Title: Mushroom compost microbial biomass: A review
Authors: T.R. Fermor and D.A. Wood


Basic nutritional requirements for growth in pure culture of Agaricus bisporus (Lange) Imbach are broadly known. Its commercial production medium, usually based on composted straw, is prepared so that it is selective for mushroom mycelial growth. Successful mycelial colonisation and degradation of this medium by A. bisporus is dependent on several ecophysiological factors, but these factors do not completely explain selectivity in chemical or biological terms. Micro-organisms and their metaboUc products present in compost may stimulate mushroom mycelial growth.

Electron microscopy has shown that a straw coating, of microbial origin, containing carbohydrate, protein and phenolic components builds up during composting and that half of this disappears within one month of spawning. A. bisporus can degrade both live and dead microorganisms in vitro using a range of extracellular bacteriolytic enzymes. The total microbial biomass in compost at spawning is estimated to be 2% of compost dry weight. It is thus not an important carbon source, but may be a concentrated source of nitrogen, lipids and other growth requirements for the initial colonisation of compost by mushroom mycelium. Radio-labelling of microbial biomass shows that Agaricus can efficiently degrade this nutrient source in situ.

These findings may be of significance for analysis of controlled environment composts produced in bulk tunnels. These may differ greatly from conventional 2-phase composts in appearance.

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