Effect of Copper and Zinc Addition to Peat Casing on A. Blazei Murrill Production

Abstract

The use of peat, as a casing material, in the Agaricus spp. mushroom industry is a common practice. Sphagnum peat moss is the most employed, often mixed with other peat types or materials such as charcoal, and amended with calcium carbonate (pH adjustment) and water (ca. 75 %), and applied on top of the mushroom colonized substrate bed to retain water on the growing beds and to promote mushroom fruit body formation. Agaricus blazei Murrill is an edible mushroom highly appreciated in the medicinal worldwide market, mainly for its immune stimulating effects. It is also known as an efficient metal accumulator; particularly, copper and zinc can be absorbed by its mycelium and assimilated into metal organic compounds, which are accumulated into the mushroom carpophores, then resulting in a metal bioavailable source with a potential use as dietary supplements. Copper and zinc are essential to human health, based on their role in metalloenzymes and as cofactors of a large number of enzymes. Lack or deficiency of these metals may cause certain illnesses or physiological disorders, while the excess can be highly toxic. The aims of this study were to evaluate the possibility to obtain Agaricus blazei fruit bodies enriched with copper or zinc, following the addition of the salt solutions of these oligoelements into the peat moss during the casing preparation or when watering the casing bed, thus challenging their growing mycelia with different doses (100 ppm or 200 ppm Cu2+ or Zn2+), and to evaluate the mycelium growth, mushroom productivity and metal bioavailability from these enriched mushrooms.