Metal tolerance and biosorption potential of filamentous fungi isolated from metal contaminated agricultural soil.
Heavy metal analysis of agricultural field soil receiving long-term (>20 years) application of municipal and industrial wastewater showed two- to five-fold accumulation of certain heavy metals as compared to untreated soil. Metal-resistant fungi isolated from wastewater-treated soil belonged to genera Aspergillus, Penicillium, Alternaria, Geotrichum, Fusarium, Rhizopus, Monilia and Trichoderma. Minimum inhibitory concentrations (MIC) for Cd, Ni, Cr, Cu, and Co were determined. The MIC ranged from 0.2 to 5 mg ml(-1) for Cd, followed by Ni (0.1-4 mg ml(-1)), Cr (0.3-7 mg ml(-1)), Cu (0.6-9 mg ml(-1)) and for Co (0.1-5 mg ml(-1)) depending on the isolate. Aspergillus and Rhizopus isolates were tested for their metal biosorption potential for Cr and Cd in vitro. Biosorption experiments were conducted with initial metal concentrations of 2, 4, 6 and 8 mM with a contact time of 4 h and wet fungal biomass (1-5 g) at 25 degrees C. Maximum biosorption of Cr and Cd ions was found at 6 mM initial metal concentration. Aspergillus sp.1 accumulated 1.20 mg of Cr and 2.72 mg of Cd per gram of biomass. Accumulation of these two metals by very tolerant Aspergillus sp.2 isolate was at par with relatively less tolerant Aspergillus sp.1 isolate. Rhizopus sp. accumulated 4.33 mg of Cr and 2.72 mg of Cd per g of biomass. The findings indicated promising biosorption of cadmium and chromium by the Rhizopus and Aspergillus spp. from aqueous solution. There is little, if any, correlation between metal tolerance and biosorption properties of the test fungi.
Zafar
Shaheen
S
Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh 202 002, India.
Aqil
Farrukh
F
Ahmad
Iqbal
I
D000222:Adaptation, Physiological; D018533:Biomass; D005658:Fungi / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D008670:Metals / Q000633:toxicity*; D012989:Soil Pollutants / Q000633:toxicity*; D013045:Species Specificity
D008670:Metals; D012989:Soil Pollutants