Fungal consortia contained Aspergillus niger, Penicillium sp. and Rhizopus sp. have shown the production of metal chelating compounds mainly oxalic acid and citric acid. Fungi show evoked responses to counter metal toxicity by suitable alterations of certain enzymes and several biomolecules. Increased synthesis of proline, malondialdehyde and catalase enzymes by metal treated fungi indicates its significance in heavy metals detoxification. The concentration of these enzymes increased with increase in metal concentration. But at very high metal concentration, the synthesis of these enzymes gets reduced.
Production of oxalic acid by fungal consortia was more in presence of Cu2++Pb2+ followed by Pb2+ and Cu2+. Fungal consortia showed decreased citric acid production with increasing in concentration of Pb2+, Cu2+ and Cu2++Pb2+. Except Pb2+, the production of proline was high in Cu2+and Cu2++Pb2+ treated fungal consortia up to 250 mg/L metal concentration. The increased synthesis of malondialdehyde (MDA) was observed after 96 hr growth of fungal consortia in heavy metals containing medium. MDA content was increased up to 100 mg/L metal concentration and above this concentration production of MDA remains constant. Increased catalase activity was observed at 50 mg/L metal concentration and very low catalase activity was found at 100 mg/L and above concentration.