Reduction of Cr(VI) by planktonic cells and biofilm of Acinetobacter sp. (ADHR1) isolated from electroplating wastewater

Abstract

In this research it was possible to analyze the capacity of Acinetobacter sp. (ADHR1) bacteria to reduce chromium (VI). Bacteria isolated from residual effluents from automobile chrome plating processes auto parts were identified by phenotypiic and genotypic methods. ADHR1 was able to 100% reduce Cr(VI) to Cr(III), resulting in: 100–500 mg / L of Cr(VI) in a lapse of time between 18 to 24 h; likewise, it was possible to show the reduction process in concentrations of 2000 mg / L which was 73% as a result. In addition to this, it was also possible to show that planktonic cells had a greater capacity to reduce hexavalent chromium compared to biofilm cells. The ChrR gene was amplified by PCR confirming the presence of the chromate reductase enzyme. The reduction in chromium was attributed to the presence of the nicotinamide adenine dinucleotide hydrogen (NADH) dependent enzyme chromate reductase in the cytosolic fraction and in the membrane associated fraction. In conclusion, Acinetobacter sp. (ADHR1) used in the study showed great potential to reduce different concentrations of Cr(VI). This research represents a truly eco-friendly alternative in the removal of sites contaminated by metals, knowing the Acinetobacter sp. (ADHR1) has the ability to reduce Cr(VI).