ABSTRACT
We isolated an Aspergillus niger strain from polluted air, near to the Faculty of Chemical Science, UASLP,in San Luis Potosi, S.L.P. Mexico, which grows about 50% relative to control at 2 g/L of Cr(VI) (79 μg of dry weight without metal) in Lee’s minimal medium, probably is resistant to metal, and also efficiently removes 1 g/100 mL of Cr(VI) after 180 min of incubation and removes metal in 6 days in solution at 100% and 70% in contaminated earth and water samples, respectively. This strain showed an efficient capacity of reduction (100%) of 50 mg/L Cr(VI) in the growth medium after 7 days of incubation at 28°C, pH 5.3 and 6.2, 100 rpm, and with an inoculum of 8.3 mg of dry weight. The Cr(VI) reduction potential of the 674resting cells was increased by cell permeabilization. The optimum temperature and pH of chromate reductase activity of the cell-free extract were found to be 37°C and 7.0, respectively, and the activity was enhanced in the presence of 0.1 mM NADH and other electron donors. 1 mMol of metal ions such as Cu2+, Na+, Hg2+, Mg2+, Fe3+, Ca2+, and Cd2+ and respiratory inhibitors resulted in a decrease of the activity. Finally, these results suggest the potential applicability of A. niger for the remediation of Cr(VI) from polluted soils and waters.
