The Research On Biosorption And Metals-resistance Of Living Fungus

The metal biosorption is a physico-chemical phenomenon based on absorption, ion exchange, complexation or microprecipitation. Biosorption of metals has been recently receiving a great deal of attention for both its scientific novelty and application potential in environmental protection or recovery of precious metals. Many investigations have showed that intact microbial cells, living or dead,and derived microbial products,can be highly efficient absorption of metal ions, especially from diluted external concentration. There have been a number of reports on the biosorption of heavy metals. However, there have been only a few reports on living epiphyte absorption.A stain of resistance to copper and zinc with high concentration was isolated from soil of tiaolin in HuNan province. With the identification of 26S rRNA D1/D2 gene sequence, the strain was identified as Aspergillus aculeatus. This experiment used the growing fungus as adsorbent, and Cu2+, Zn2+ as adsorate. The influences of experimental conditions such as time, pH value, temperature, inditial concentration of adsorbent and adsorate on adsorbing effect are studied.Many heavy metals are the necessary elements for the microorganisms. But when the concentrations of the intercellular heavy metals are too high, the metals become poisonous. The microorganisms can minish the destroy of the toxicity by alter the componential of the membrane and enhance the superficial enrichment. Metal-resistance of microorganisms may enhance their ability to live in bad surroundings.This text maked sure the Cu2+, Zn2+ to 2# fungus'minimal inhibitory concentration (MIC). Using the electron magnifier and FTIR technic analysed the normal and absorption metals'fungus. Furthermore, the meath of iodimetric estimation was used to analyse the contents of glutathione which were cultured in different mediums. Primery research the mechanism of Metal-resistance by fungus.Its optimum growth conditions were temperature 30℃, pH 5.0, initial concentration of Cu2+ and Zn2+ 50mg/L, rate of the shaker 120r/min, cultured time 120h, the adsorption efficiency could reach 54% and 60% respectively. It can resist copper of 400mg/L and zinc of 800mg/L. The electron magnifier photos show that fungus cells appeared different degree damnification under 25mg/L Cu2+, Zn2+. The results of FTIR show that the fungus surface's–OH,phosphate,polyoses are absorption movement centers. Stress of Cu2+, Zn2+ induced fungus interior GSH's change. Under the condition of 50 mg/L Cu2+, Zn2+, GSH achieved to the maximum, respectively 0.98 and 0.88mg/g. While GSH at normal fungus only was 0.04 mg/g. It can confer that glutathione seems to play a favorable role in avoidance of heavey metal oxidation stress from the results.