Hexavalent Chromate Reduction by Locally Isolated Bacteria

Abstract

Hexavalent chromium Cr(VI) is considered a mutagenic, teratogenic and has been listed as class-A human carcinogen by the United States Environmental Protection Agency US-EPA. It is discharged into the environment from several industries such as leather tanning, metal cleaning, alloy formation and textile dyeing. Biological adsorption and reduction of Cr(VI) to relatively less toxic Cr(III) by microbial biomass is regarded as one of the most practical and useful methods for detoxification of Cr(VI). In this study 49 Cr(VI) resistant bacterial isolates were isolated from different contaminated and non-contaminated soils (Misr Al Qadima tanneries, beside Alsaad aluminum factory and Ain Shams University garden soil). They were selected on nutrient agar and starch nitrate agar media. Screening was done to select the most potent Cr(VI) reducing isolates. Among the 49 isolates three potent Cr(VI) reducing isolates (Ia3, Ia4, and Sa1) showed remarkable ability to reduce Cr(VI) at high concentration.