Bioaccumulation of chromium and nickel by fungal isolates from tannery effluent collection site from Kanpur, Uttar Pradesh, India

Abstract

Aim: The aim of study was to analyze the physicochemical properties of tannery effluent and to isolate the promising fungi from heavy metals contaminated effluent to assess their metals accumulating abilities against chromium and nickel. Materials and Methods: The physiochemical parameters of tannery wastewater were analyzed. Aspergillus niger and Penicillium species were isolated and identified on the basis of their morphological and microscopic studies. The 6 heavy metals (Ni, Cu, Cr, Pb, Hg, and As) were analyzed through atomic absorption spectrometer from collected sample. Isolated fungal strains were assessed for their tolerance level against chromium and nickel heavy metals. Minimum inhibitory concentration was determined by well diffusion plate assays in Sabouraud dextrose agar medium. Bioaccumulation of chromium and nickel was determined on the basis of left metal ion concentration in aqueous medium. Results: Total dissolved solids, total suspended solids, and chloride were found to be 21300 mg/l, 1250 mg/l, and 740 mg/l, respectively. The pH and temperature of the wastewater were recorded to be 8.3 and 31°C, respectively. Dissolved oxygen (DO), biochemical oxygen demand, and chemical oxygen demand was found to be 2.72 mg/l, 3000 mg/l, and 3584 mg/l, respectively. The heavy metals such as nickel, chromium, copper, lead, mercury, and arsenic were found to be 0.280 mg/l, 0.478 mg/l, 0.006 mg/l, 0.0001 mg/l, 6.899 μg/l, and 0.790 μg/l, respectively. Aspergillus niger and Penicillium species were isolated and identified from the tannery effluent. A. niger tolerated 600 mg/l Cr and 100 mg/l Ni. Penicillium species tolerated up to 800 mg/l Cr and 400 mg/l Ni. Accumulation of A. niger at 25 mg/l aqueous medium of chromium was found to be 50.12%, at 50 mg/l 42.76%, at 100 mg/l 27.18% while Penicillium accumulation at 25 mg/l was 27.08%, at 50 mg/l 35.68%, at 100 mg/l 27.62%. In case of nickel accumulation of A. niger at 25 mg/l aqueous medium of nickel 66.64%, at 50 mg/l 37.70%, at 100 mg/l 34.47% while Penicillium accumulation at 25 mg/l 49.92%, at 50 mg/l 44.76%, at 100 mg/l 18.02%. Conclusion: The results of the study indicated the potential of these fungi in removal of heavy metals from industrial effluents containing higher concentration of heavy metals, namely, chromium and nickel. The further studies warranted to identify different fungi species capable of bioaccumulation of toxic heavy metals.