Title: Bioremediation of Cr(VI) by Enterobacter amnigenus EA31 isolated from tannery waste contaminated soil

Authors: Hanane Sayel; Nezha Tahri Joutey; Wifak Bahafid; Naïma El Ghachtouli

Addresses: Microbial Biotechnology Laboratory, Faculty of Sciences and Technology, Sidi Mohamed Ben Abdellah University, P.O. Box 2202, Fez, Morocco ' Microbial Biotechnology Laboratory, Faculty of Sciences and Technology, Sidi Mohamed Ben Abdellah University, P.O. Box 2202, Fez, Morocco ' Microbial Biotechnology Laboratory, Faculty of Sciences and Technology, Sidi Mohamed Ben Abdellah University, P.O. Box 2202, Fez, Morocco ' Microbial Biotechnology Laboratory, Faculty of Sciences and Technology, Sidi Mohamed Ben Abdellah University, P.O. Box 2202, Fez, Morocco

Abstract: A novel chromium resistant and reducing bacterium was isolated from tannery waste contaminated soil. On the basis of different morphological, biochemical characteristics and 16S rRNA gene analysis the strain was identified as Enterobacter amnigenus EA31. The strain reduced Cr(VI) under a wide range of concentrations from 100 to 400 mg/L with a maximumat 100 mg/L. Optimum temperature and pH being 37°C and 9 respectively for maximum chromium reduction. The bacterial culture were repeatedly added with 25 mg/L Cr(VI) until saturation in Cr(VI) reduction was observed. Repeated detoxification of 25 mg/L Cr(VI) could be achieved up to three consecutive inputs. The suspended culture repeatedly reduced 25 mg/L Cr(VI) within 6 h up to three consecutive inputs. The reduction of chromium occurred even in the presence of high concentration of other heavy metals. Assay with resting and permeabilised cells (treated with toluene and Triton X-100) demonstrated that Cr(VI) reduction activity was soluble and not tightly bound to the cell membrane. Inoculation with E. amnigenus improved the growth parameters of wheat and clover under chromium stress. The results suggest that E. amnigenus can be exploited for bioremediation of chromium under various environmental conditions.

Keywords: Cr(VI) reduction; Enterobacter amnigenus; Cr(VI) detoxification; heavy metals resistance; plant growth; bioremediation; tannery waste; soil contamination; environmental pollution; chromium dioxide; chromium(IV) oxide; bacterial culture; wheat growth; clover growth; chromium stress.

DOI: 10.1504/IJEE.2016.082304

International Journal of Environmental Engineering, 2016 Vol.8 No.2/3, pp.124 - 138

Accepted: 11 Apr 2016
Published online: 14 Feb 2017 *

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