An Investigation on Tolerance and Biosorption Potential of Aspergillus awamori ZU JQ 965830.1 to Cu(II)

THE MINIMUM inhibitory concentration (MIC) value of A.awamori for Cu(II) was 3100mg/l and a complete inhibition of biomass production was observed at 800mg/l concentration of Cu(II). Slight changes were observed by SEM investigation in Cu(II)-stressed biomass. Quantification of Cu(II) was performed by EDAX. Transmission electron microscopy investigation (TEM) confirmed the involvement of extracellular adsorption, intracellular penetration through the cell wall and vacuolation. Cu(II) stress induced noticeable changes in the activities of polyphenol oxidase(PPO), glutathione reductase (GR) and peroxidase (POD) and in the concentration of total antioxidant, soluble protein and thiol. High performance liquid chromatography analysis (HPLC) revealed that Cu(II) stress stimulated the production of oxalic acid .Maximum Cu(II) uptake capacity was achieved at pH 4.0, initial metal ion concentration 500mg/l and biomass dosage 1g/l. Maximum Cu(II) uptake capacities were reached after 180 min for live biomass and 30 min for dead biomass. Fourier transform infrared spectroscopy (FTIR) results gave an indication of chelation between oxygen-, nitrogen-, phosphorus- and especially sulphur-containing ligands of biomass with metal ions. X-ray diffraction analysis (XRD) revealed the presence of CuSO4.H2O in live and dead biomass. EDAX confirmed the occurrence of sulphur, oxygen and Cu(II) in the cell wall