Evaluation of bioremediation and detoxification potentiality of Aspergillus niger for removal of hexavalent chromium in soil microcosm

Aspergillus niger isolated from soil of leather tanning effluent had higher activity to remove chromium then the other fungal isolates. The potency of A. niger was evaluated in shake flask culture by absorption of chromium at pH 6, temperature 30 °C. The toxicity of chromium evaluated in petriplates and soil microcosm seed bioassay test had indicated increase in toxicity with the higher concentration of chromate. A. niger introduced in soil microcosm (40% moisture content) with different concentration of chromate (250, 500, 1000, 1500 and 2000 ppm) removed more than 70% chromium in soil contaminated by 250 and 500 ppm of chromate. However, chromium-contaminated soil (2000 ppm of potassium chromate) mixed with compost (5% and 10%) significantly removed chromium in presence of fungus, A. niger. The results of chromate toxicity in the wheat plants revealed that the peroxidases was induced due to increase of metal stress which was reversed in soil microcosm amended with compost.