Débora Figlas

Growth and productivity of different Pleurotus ostreatus strains on sunflower seed hulls supplemented with N–NH4+ and/or Mn(II)

The mycelial growth rates in lineal growth assay, yield, and production rate of five Pleurotus ostreatus strains were evaluated in response to different levels of Mn(II) and/or NH4+ in a substrate containing sunflower seed hulls as a main energy and nutritional component. Each strain showed different basal values for mycelial growth rate and biological efficiency on sunflower seed-hull substrate. Adding growth limiting mineral nutrients increased the mycelial growth rate by 13-25%. Primordia initiation for the first flush appeared between day 24 and 28 and days to the second crop ranged from 39 to 51. Biological efficiency increased over control values and reached 60-112%, depending on the strain and the concentration of Mn(II) and NH4+. This study demonstrated the advantage of selecting the most productive P. ostreatus strains in a substrate formulated with sunflower seed hulls to provide the main energy and nutritional ingredients and supplemented with Mn(II) and/or NH4+.

Bioaccumulation and Bioavailability of Copper and Zinc on Mineral-Enriched Mycelium of Grifola frondosa

Grifola frondosa is an edible and medicinal mushroom. The bioaccumulation and potential biovailability of Cu and Zn were studied to obtain mycelium with potential properties as a food dietary supplement. Mycelia grown in the presence of nonmycotoxic concentrations of 100 and 200 ppm of Cu or 25 and 50 ppm of Zn accumulated 200-322 ppm and 267-510 ppm of Cu or Zn, respectively. When these enriched metal mycelia were subjected in vitro to a simulated gastrointestinal digestion, the solubility in these digestive fluids was 642-669 ppm and 102-530 ppm, which represent 32-33% and 0.7-3.5% of the recommended daily intake (RDI) for Cu and Zn, respectively, in 1 g of mycelium. These results are discussed in relation to the RDI values exhibited by two commercial supplements, and arguments are given on the potential use of these mineral-enriched mycelia in capsules (in the case of Cu-enriched mycelia), in food preparations, and also as a component of cosmetic mixtures.

Copper and Zinc Bioaccumulation and Bioavailability of Ganoderma lucidum

Ganoderma lucidum is a widely recognized medicinal mushroom. The bioaccumulation and potential bioavailability of copper (Cu) and zinc (Zn), which are essentials for human health, were analyzed in G. lucidum mycelium and fruit bodies grown in the presence of these metals to test their potential utility as a food dietary supplement. Mycelia grown in culture medium with non-mycotoxic doses of Cu or Zn (25 and 50 mg/kg) were selected for evaluation of the bioavailability of these metals in the gastrointestinal tract by using an in vitro simulated digestion system. One gram of dried mycelium grown in the presence of 50 mg/kg Cu or Zn showed a bioavailability of 19% for Cu and 2% for Zn of the recommended daily intake (RDI). When production of fruit bodies was evaluated, the highest biological efficiency (23%) was reached when the substrate was enriched with 100 mg/kg Cu. Cu and Zn contents obtained either before or after digestion of fruit bodies from all metal-enriched treatments were substantially lower than those from metal-enriched mycelia. The metal bioavailability was also low: 1.5% of the Cu RDI and almost negligible for Zn. The results are discussed in relation to the RDI values exhibited by two commercial supplements. The potential incorporation of these mineral-enriched mycelia/fruit bodies in capsules, infusions, and dietary supplements is evaluated.