Cover Image

Mechanisms of bacterial detoxification of Cr(VI) from industrial wastewater in the presence of industrial effluent as potential energy source

Chromium (Cr), especially Cr(VI) is of particular environmental concern owing to its high solubility, bioavailability and toxicity. The reduction of Cr(VI) to innocuous Cr(III) is an important step in the remediation of Cr(VI)-contaminated environments. The understanding of how microorganisms resist...

Full description

Saved in:
Bibliographic Details
Main Authors: Ahmad, Wan Azlina, Shahir, Shafinaz, Zakaria, Zainul Akmar
Format: Monograph
Language:English
Published: Faculty of Science 2009
Subjects:
Q Science (General)
Online Access:http://eprints.utm.my/id/eprint/9753/1/78176.pdf
http://eprints.utm.my/id/eprint/9753/
Tags: Add Tag
No Tags, Be the first to tag this record!
id my.utm.9753
record_format eprints
spelling my.utm.97532011-05-10T05:18:12Z http://eprints.utm.my/id/eprint/9753/ Mechanisms of bacterial detoxification of Cr(VI) from industrial wastewater in the presence of industrial effluent as potential energy source Ahmad, Wan Azlina Shahir, Shafinaz Zakaria, Zainul Akmar Q Science (General) Chromium (Cr), especially Cr(VI) is of particular environmental concern owing to its high solubility, bioavailability and toxicity. The reduction of Cr(VI) to innocuous Cr(III) is an important step in the remediation of Cr(VI)-contaminated environments. The understanding of how microorganisms resist metals can provide insight into strategies for their detoxification or removal from the environment. The present investigation was undertaken to study the Cr(VI) resistance mechanisms by Acinetobacter haemolyticus, a strain isolated from Cr(VI)-containing textile wastewater. In preliminary studies, the strain was shown to be able to tolerate Cr(VI) concentrations of 30 and 90 mg L-1 in Luria-Bertani (LB) agar and broth respectively. The Cr(VI) reduction capacity of A. haemolyticus was found to be greater when grown in higher percentage of LB broth than minimal salts broth. The Cr(VI) reduction also increased with lower initial concentration of Cr(VI) added after 5 hours. The x-ray absorption fine structure (XAFS) analysis displayed the ability of the strain to reduce Cr(VI) to Cr(III) which was octahedrally coordinated to oxygen. The Cr(III) was most likely to form complexes with carboxyl (COO-) groups from the biomass based on Fourier-transform infrared (FTIR) analysis. The FTIR analysis also showed interactions of chromium with amino and hydroxyl groups. Field-emission scanning electron microscope (FESEM) showed that cells grown in the presence of Cr(VI) had a wrinkled appearance with a significant increase in size. No precipitates were found on the cell surface. However, precipitates were observed in the cytoplasmic region of the cells via transmission electron microscope (TEM) analysis, suggesting the transport of Cr(VI) into the cytoplasm and intracellular Cr(VI) reduction. Intracellular reduction of Cr(VI) was supported by a reductase test using soluble crude cell - free extracts. The specific reductase activity obtained was 0.52 μg Cr(VI) reduced per mg of protein an hour at pH 7.2 and 37 ˚C. In plasmid screenings, the strain was found to harbor a plasmid of about 12 kb. The findings showed that Cr(VI) resistance mechanisms of A. haemolyticus include the reduction of Cr(VI) to Cr(III), and intra- and extracellular sequestration of chromium. Faculty of Science 2009-12-31 Monograph NonPeerReviewed application/pdf en http://eprints.utm.my/id/eprint/9753/1/78176.pdf Ahmad, Wan Azlina and Shahir, Shafinaz and Zakaria, Zainul Akmar (2009) Mechanisms of bacterial detoxification of Cr(VI) from industrial wastewater in the presence of industrial effluent as potential energy source. Project Report. Faculty of Science, Skudai, Johor. (Unpublished)
institution Universiti Teknologi Malaysia
building UTM Library
collection Institutional Repository
continent Asia
country Malaysia
content_provider Universiti Teknologi Malaysia
content_source UTM Institutional Repository
url_provider http://eprints.utm.my/
language English
topic Q Science (General)
spellingShingle Q Science (General)
Ahmad, Wan Azlina
Shahir, Shafinaz
Zakaria, Zainul Akmar
Mechanisms of bacterial detoxification of Cr(VI) from industrial wastewater in the presence of industrial effluent as potential energy source
description Chromium (Cr), especially Cr(VI) is of particular environmental concern owing to its high solubility, bioavailability and toxicity. The reduction of Cr(VI) to innocuous Cr(III) is an important step in the remediation of Cr(VI)-contaminated environments. The understanding of how microorganisms resist metals can provide insight into strategies for their detoxification or removal from the environment. The present investigation was undertaken to study the Cr(VI) resistance mechanisms by Acinetobacter haemolyticus, a strain isolated from Cr(VI)-containing textile wastewater. In preliminary studies, the strain was shown to be able to tolerate Cr(VI) concentrations of 30 and 90 mg L-1 in Luria-Bertani (LB) agar and broth respectively. The Cr(VI) reduction capacity of A. haemolyticus was found to be greater when grown in higher percentage of LB broth than minimal salts broth. The Cr(VI) reduction also increased with lower initial concentration of Cr(VI) added after 5 hours. The x-ray absorption fine structure (XAFS) analysis displayed the ability of the strain to reduce Cr(VI) to Cr(III) which was octahedrally coordinated to oxygen. The Cr(III) was most likely to form complexes with carboxyl (COO-) groups from the biomass based on Fourier-transform infrared (FTIR) analysis. The FTIR analysis also showed interactions of chromium with amino and hydroxyl groups. Field-emission scanning electron microscope (FESEM) showed that cells grown in the presence of Cr(VI) had a wrinkled appearance with a significant increase in size. No precipitates were found on the cell surface. However, precipitates were observed in the cytoplasmic region of the cells via transmission electron microscope (TEM) analysis, suggesting the transport of Cr(VI) into the cytoplasm and intracellular Cr(VI) reduction. Intracellular reduction of Cr(VI) was supported by a reductase test using soluble crude cell - free extracts. The specific reductase activity obtained was 0.52 μg Cr(VI) reduced per mg of protein an hour at pH 7.2 and 37 ˚C. In plasmid screenings, the strain was found to harbor a plasmid of about 12 kb. The findings showed that Cr(VI) resistance mechanisms of A. haemolyticus include the reduction of Cr(VI) to Cr(III), and intra- and extracellular sequestration of chromium.
format Monograph
author Ahmad, Wan Azlina
Shahir, Shafinaz
Zakaria, Zainul Akmar
author_facet Ahmad, Wan Azlina
Shahir, Shafinaz
Zakaria, Zainul Akmar
author_sort Ahmad, Wan Azlina
title Mechanisms of bacterial detoxification of Cr(VI) from industrial wastewater in the presence of industrial effluent as potential energy source
title_short Mechanisms of bacterial detoxification of Cr(VI) from industrial wastewater in the presence of industrial effluent as potential energy source
title_full Mechanisms of bacterial detoxification of Cr(VI) from industrial wastewater in the presence of industrial effluent as potential energy source
title_fullStr Mechanisms of bacterial detoxification of Cr(VI) from industrial wastewater in the presence of industrial effluent as potential energy source
title_full_unstemmed Mechanisms of bacterial detoxification of Cr(VI) from industrial wastewater in the presence of industrial effluent as potential energy source
title_sort mechanisms of bacterial detoxification of cr(vi) from industrial wastewater in the presence of industrial effluent as potential energy source
publisher Faculty of Science
publishDate 2009
url http://eprints.utm.my/id/eprint/9753/1/78176.pdf
http://eprints.utm.my/id/eprint/9753/
_version_ 1643645244043952128
score 13.211869

Similar Items