Silver uptake by Agaricus bisporus from an artificially enriched substrate.

The champignon mushroom Agaricus bisporus was cultivated on compost (wheat and rye straw, hens' manure, gypsum, urea and peat) artificially fortified with silver nitrate added at four different concentrations (0.01, 0.1, 1.0 and 10.3 mg/kg) and 0 mg/kg (control) on a dry weight basis. The method of measurement was flame atomic absorption spectrophotometry after dry ashing of the samples at 420 degrees C and dissolving the residue in 1 M nitric acid. The highest concentration of silver, reaching between 120 +/- 30-150 +/- 36 mg/kg on a dry weight basis, was observed in fruit bodies grown on the most contaminated substrate containing 10.3 mg added Ag/kg dry weight. The silver concentration in caps/stalks/whole fruit bodies of A. bisporus was positively correlated (r = 0.72; P < 0.001) with an increasing level of fortification of the substrate. The bioconcentration factor (BCF) of silver in caps/stalks/whole fruit bodies of A. bisporus was inversely correlated (-0.44 < r < -0.36; 0.001 < p < 0.01) with the silver concentration of the contaminated substrate. The highest silver BCF value of 120-230 has been observed in caps and stalks of mushrooms grown on a substrate enriched with 0.01 mg Ag/kg dry weight. Silver ion added to the substrate in concentrations up to 10.3 mg/kg on a dry weight basis exhibited no observable toxic effect against the mycelial growth and fruiting of A. bisporus.