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

Antioxidant, antibacterial and anti-aging activities of intracellular zinc polysaccharides from Grifola frondosa SH-05

In present work, the strain of Grifola frondosa SH-05 was used as a vector of zinc biotransformation to produce the IZPS. The bioactivities including antioxidant and antibacterial activities in vitro and anti-aging properties in vivo of IZPS were investigated comparing with the IPS. The results which were in consistent with the results of histopathology assay demonstrated that the IZPS had superior antioxidant and anti-aging activities by scavenging the hydroxyl and DPPH radicals, increasing enzyme activities, decreasing the MDA contents and ameliorating the anile condition of mice. Besides, the IZPS also showed potential antibacterial activities. The IZPS with higher bioactivities was composed of were Rha, Ino and Glu with a molar ratio of 4.7:3.6:1. These conclusions indicated that the IZPS might be a potential source of natural antioxidant, antibacterial agent and anti-aging agent.

Optimization of Mycelia Selenium Polysaccharide Extraction from Agrocybe cylindracea SL-02 and Assessment of their Antioxidant and Anti-Ageing Activities

The aim of the present study was to optimize the purification of mycelia selenium polysaccharides (MSPS) from Agrocybe cylindracea SL-02 and characterize their in vitro antioxidant and in vivo anti-ageing activities. The Box-Behnken experimental design (BBD) was evaluated, which showed that the optimum conditions included an extraction temperature of 94.99°C, a pH of 9 and a precipitation temperature of 12°C, and the predicted yield was 11.036 ± 0.31%. The in vitro antioxidant assay demonstrated that MSPS had potential effects on scavenging and enhanced the reducing power of reactive oxygen species. The in vivo anti-ageing evaluation showed that MSPS significantly reduced the malonaldehyde (MDA) contents and total cholesterol (CHOL) levels, and remarkably improved the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and total antioxidant capacity (T-AOC) in mice in response to D-galactose-induced ageing. Furthermore, the characteristic analysis of MSPS indicated a selenium content of 1.76 ± 0.10 mg/g at a concentration of 6 μg/mL in liquid media and a monosaccharide composition of rhamnose, arabinose, mannose, glucose and galactose at a molar ratio of 29:3:1:18.8:2.7. These results suggest that MSPS might be suitable for functional foods and natural drugs on preventing the ageing progress induced by toxic chemicals.

Iron bioaccumulation in mycelium of Pleurotus ostreatus

Pleurotus ostreatus is able to bioaccumulate several metals in its cell structures; however, there are no reports on its capacity to bioaccumulate iron. The objective of this study was to evaluate cultivation variables to increase iron bioaccumulation in P. ostreatus mycelium. A full factorial design and a central composite design were utilized to evaluate the effect of the following variables: nitrogen and carbon sources, pH and iron concentration in the solid culture medium to produce iron bioaccumulated in mycelial biomass. The maximum production of P. ostreatus mycelial biomass was obtained with yeast extract at 2.96 g of nitrogen L ⁻¹ and glucose at 28.45 g L ⁻¹ . The most important variable to bioaccumulation was the iron concentration in the cultivation medium. Iron concentration at 175 mg L ⁻¹ or higher in the culture medium strongly inhibits the mycelial growth. The highest iron concentration in the mycelium was 3500 mg kg ⁻¹ produced with iron addition of 300 mg L ⁻¹ . The highest iron bioaccumulation in the mycelium was obtained in culture medium with 150 mg L ⁻¹ of iron. Iron bioaccumulation in P. ostreatus mycelium is a potential alternative to produce non-animal food sources of iron.

Improvement of zinc bioaccumulation and biomass yield in the mycelia and fruiting bodies of Pleurotus florida cultured on liquid media

The effect of different concentrations of zinc on the bioaccumulation of zinc and biomass yield in both mycelium and fruiting body of Pleurotus florida cultivated in liquid medium was studied. The results showed that the optimum yield of mycelia (11.33 ± 0.44 g/L) and fruiting bodies (7.70 ± 0.19 g/L) dry biomass was obtained in a liquid medium containing 100 mg/L of zinc. At a zinc concentration of 200 mg/L, the highest concentration of zinc in the mycelia and fruiting bodies reached 1.869 ± 0.115 and 0.151 ± 0.008 mg/g dry weight, respectively. The addition of zinc to the culture media significantly reduced zinc bioaccumulation factor in mycelia (from 24.64 ± 0.52 to 3.35 ± 0.24) and fruiting bodies (from 36.71 ± 0.30 to 0.49 ± 0.02) dry weight. Our findings indicated that the ability of zinc bioaccumulation in the mycelia is much higher than in the fruiting bodies. The fundamental information obtained in this study will be useful for the improvement of zinc bioaccumulation and biomass yield in mycelia and fruiting bodies of P. florida cultivated in liquid media to obtain maximum zinc-enriched biomass.

The in vitro digestibility and absorption of magnesium in some edible seaweeds

BACKGROUND

Many edible seaweeds are rich in magnesium (Mg). However, Mg absorption is low in some seaweeds because fibers in these seaweeds suppress Mg absorption. We hypothesize that Mg absorption from some other seaweeds is not low because of the diversity of fibers. We measured Mg concentration and Mg solubility after in vitro digestion in edible seaweeds, Aosa (Ulvaceae pertusa), Kombu (Laminaria japonica) and Funori (Gloiopeltis furcata). Then we determined Mg absorption in rats given diets containing these seaweeds or magnesium oxide as the major source of Mg, and calculated Mg absorption from seaweeds.

RESULTS

The fractional apparent absorption of Mg in seaweeds was Kombu = magnesium oxide > Aosa = Funori. Mg concentration was Aosa > Kombu and Funori had an intermediate amount of Mg, while Mg solubility after in vitro digestion was Funori = Kombu > Aosa. Consequently, the absorbable Mg concentration was Aosa = Kombu > Funori.

CONCLUSION

The absorption of Mg from different seaweeds differs and is not affected by the Mg solubility alone. The absorbable Mg concentration was high in Aosa and in Kombu, indicating that Aosa and Kombu are good sources of Mg.

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.