Study On Bioconcentration And Tolerance Of Cd ~ Sup> 2 + Mycelia Of Boletus Edulis

In this study, we explored the effects of cadmium stress on Boletus edulis mycelium under the fermentation controlled conditions in the laboratory. We determined the changes of total soluble sugar, soluble proteins, polysaccharides, and the content of antioxidant enzymes in the mycelium. By studying the antioxidant activity of polysaccharides in vitro under cadmium stress, we tested the composition of monosaccharide and amino acid content changes within the bacterial cells. The results show that:Treated with different concentrations of Cd2+, we recorded the growing situation of Boletus edulis mycelium on PDA plates:with increasing concentrations of cadmium, compared to the control group which Boletus edulis mycelium growing better with white color, in the treatment group, Boletus edulis mycelial colony circle became smaller, the hyphae became thinner and the color began to turn yellow, and the mycelium near the vaccination center appeared "brown circle". The cadmium half inhibitory concentration on Boletus edulis mycelial is 35.77mg/L. With increasing concentrations of Cd, mycelium dry weight showed a continued downward trend, and the half inhibitory concentration of Cd2+on the dry weight of Boletus edulis is 56mg/L,With the increasing concentration of the treatment, Boletus edulis mycelium of Cd2+bioaccumulation volume showed "S" shaped curve, and the adsorption capacity is 3408.9mg/kg DW.Different concentrations of cadmium treatment significantly affected the total soluble sugar and soluble protein conten in Boletus edulis mycelium. The total soluble sugar content showed the trend of increased at first and then decreased. Effect of cadmium treatment of bacterial soluble protein content and total sugar is completely the opposite that the soluble protein content reduced after the first increase. With the increasing concentration of Cd2+, SOD activity in Boletus edulis mycelium presented the trend of "Low promotion high suppression", and the CAT activity also showed the same changes, but the change is not significant. In this study, POD activity was significantly decreased with increasing concentrations of Cd2+treatment, it may be related with the high concentration of Cd2+, so we can’t observe the activation on POD activity of the Cd2+treatment.In this study, we measured seven monosaccharide standard products, and six kinds of monosaccharide were measured in Boletus edulis mycelium, Glucose is the main component, followed by galactose, mannose, rhamnose, and xylose and rock fucose content is relatively low, while arabinose is not detected. DPPH radical scavenging activity of polysaccharides has increased to some extent with Cadmium joining in Boletus edulis mycelia; hydroxyl radical scavenging activity has significantly (p<0.05) increased, which showed the trend of low promotion and high suppression; ABTS·+ radical scavenging activity increase with the gradually increased cadmium concentration, which was to the control group were significantly different (p <0.05); FRAP value increased first and then decreased, and the difference was significant (p<0.05). We extracted and determined the free proline content of Boletus edulis mycelium, the results showed that with increasing Cd2+ concentrations showed "S" shaped curve, while the total free amino acid content increased after the first lower.