Effects of Zn supplementation on the growth, amino acid composition, polysaccharide yields and anti-tumour activity of Agaricus brasiliensis

The effects of Zn supplementation on the growth, amino acid composition, polysaccharide yields and anti-tumour activity of Agaricus brasiliensis were studied. An initial Zn concentration within the range of 0-300 mg/l had a significant effect on the cell growth and Zn biosorption. At an initial Zn concentration of 300 mg/l, a maximal extracellular polysaccharide (EPS) yield of 5.08 +/- 0.25 g/l was obtained, as well as a maximal intracellular polysaccharide (IPS) of 12.25 +/- 0.31 mg/g DW. Amino acid analysis results showed that the total amino acid contents of mycelia and culture filtrate decreased from 1090.08 +/- 0.76 (233.62 +/- 0.06) to 1077.40 +/- 0.77 mg/100 g DW (229.52 +/- 0.05 mg/l), respectively, while the total essential amino acid contents of mycelia and culture filtrate markedly increased from 429.51 +/- 0.86 (58.84 +/- 0.05) to 476.9 +/- 0.85 mg/100 g DW (59.99 +/- 0.04 mg/l), respectively. The anti-tumour activity of Zn-enriched mycelial powder against sarcoma 180 in mice showed that the tumour inhibition ratio was 61.5% and was enhanced markedly as compared to normal mycelial powder of 30.8. The fundamental information obtained in this study will be useful for efficient production of Zn-enriched foods or drugs.