Cover Image

Chromate reductase activity in whole cells and crude cell free extract of Acinetohacter Haemolyticus

Extensive use of hexavalent chromium, (Cr(VI)) in various industrial applications is a threat to human health, living resources and ecological system due to its high solubility, toxicity and carcinogenic effects. Previously, one locally isolated Cr(VI) reducing-resistant bacteria, Acinetobacter haem...

Full description

Saved in:
Bibliographic Details
Main Author: Abdul Karim, Norsuhada
Format: Thesis
Language:English
Published: 2012
Subjects:
QD Chemistry
Online Access:http://eprints.utm.my/id/eprint/32395/1/NorsuhadaAbdulKarimMFS2012.pdf
http://eprints.utm.my/id/eprint/32395/
http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:68009?site_name=Restricted Repository
Tags: Add Tag
No Tags, Be the first to tag this record!
id my.utm.32395
record_format eprints
spelling my.utm.323952017-09-20T00:41:51Z http://eprints.utm.my/id/eprint/32395/ Chromate reductase activity in whole cells and crude cell free extract of Acinetohacter Haemolyticus Abdul Karim, Norsuhada QD Chemistry Extensive use of hexavalent chromium, (Cr(VI)) in various industrial applications is a threat to human health, living resources and ecological system due to its high solubility, toxicity and carcinogenic effects. Previously, one locally isolated Cr(VI) reducing-resistant bacteria, Acinetobacter haemolyticus was used in the ChromeBac™ system, to remove toxic Cr(VI) from industrial wastewater. However, this process required long retention time which was primarily due to the toxicity of Cr(VI) towards immobilized whole cells used. The use of enzymes can be a suitable option for the effective Cr(VI) reduction as compared to whole cells. In view of this, this study was conducted to assess in vitro characterization of the enzymatic chromate reductase activity in cell free-extract (CFE) for maximum activity of Cr(VI) reduction. Cr(VI) resistance and reduction of A. haemolyticus was evaluated in Luria-Bertani (LB) medium supplemented with various Cr(VI) concentrations. From the results, A. haemolyticus can resist up to 200 mg/L Cr(VI) in LB broth compared to 100 mg/L Cr(VI) in LB agar. The FTIR and FESEM-EDX analysis suggested Cr deposition onto the bacterial cells surface via complex formation between Cr species and either carboxyl, hydroxyl or amide groups. TEM analysis showed that Cr(III) is also distributed in membrane and cytosolic fractions of bacteria. ESR analysis revealed that chromium accumulated on bacterial surface and mostly as Cr(III). The enzyme activity was optimal at 30°C and pH 7 in the presence of 1 mM Co2+. The Michaelis-Menten constants, Km and maximum reaction rate, Vmax obtained from the Lineweaver-Burke plot were 184.47 µM and 33.3 nmol/min/mg protein in the presence of 1 mM Co2+. Optimum Cr(VI) reduction by immobilized CFE-alginate was determined at initial pH 3, 100 rpm and 5 g wet weight beads dosage. Although immobilized enzyme system was able to reduce Cr(VI), the performance was not as good as the free enzyme. This study showed higher Cr(VI) reduction performance by free CFE compared to the use of whole cells demonstrate its potential for industrial application. 2012-12 Thesis NonPeerReviewed application/pdf en http://eprints.utm.my/id/eprint/32395/1/NorsuhadaAbdulKarimMFS2012.pdf Abdul Karim, Norsuhada (2012) Chromate reductase activity in whole cells and crude cell free extract of Acinetohacter Haemolyticus. Masters thesis, Universiti Teknologi Malaysia, Faculty of Science. http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:68009?site_name=Restricted Repository
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 QD Chemistry
spellingShingle QD Chemistry
Abdul Karim, Norsuhada
Chromate reductase activity in whole cells and crude cell free extract of Acinetohacter Haemolyticus
description Extensive use of hexavalent chromium, (Cr(VI)) in various industrial applications is a threat to human health, living resources and ecological system due to its high solubility, toxicity and carcinogenic effects. Previously, one locally isolated Cr(VI) reducing-resistant bacteria, Acinetobacter haemolyticus was used in the ChromeBac™ system, to remove toxic Cr(VI) from industrial wastewater. However, this process required long retention time which was primarily due to the toxicity of Cr(VI) towards immobilized whole cells used. The use of enzymes can be a suitable option for the effective Cr(VI) reduction as compared to whole cells. In view of this, this study was conducted to assess in vitro characterization of the enzymatic chromate reductase activity in cell free-extract (CFE) for maximum activity of Cr(VI) reduction. Cr(VI) resistance and reduction of A. haemolyticus was evaluated in Luria-Bertani (LB) medium supplemented with various Cr(VI) concentrations. From the results, A. haemolyticus can resist up to 200 mg/L Cr(VI) in LB broth compared to 100 mg/L Cr(VI) in LB agar. The FTIR and FESEM-EDX analysis suggested Cr deposition onto the bacterial cells surface via complex formation between Cr species and either carboxyl, hydroxyl or amide groups. TEM analysis showed that Cr(III) is also distributed in membrane and cytosolic fractions of bacteria. ESR analysis revealed that chromium accumulated on bacterial surface and mostly as Cr(III). The enzyme activity was optimal at 30°C and pH 7 in the presence of 1 mM Co2+. The Michaelis-Menten constants, Km and maximum reaction rate, Vmax obtained from the Lineweaver-Burke plot were 184.47 µM and 33.3 nmol/min/mg protein in the presence of 1 mM Co2+. Optimum Cr(VI) reduction by immobilized CFE-alginate was determined at initial pH 3, 100 rpm and 5 g wet weight beads dosage. Although immobilized enzyme system was able to reduce Cr(VI), the performance was not as good as the free enzyme. This study showed higher Cr(VI) reduction performance by free CFE compared to the use of whole cells demonstrate its potential for industrial application.
format Thesis
author Abdul Karim, Norsuhada
author_facet Abdul Karim, Norsuhada
author_sort Abdul Karim, Norsuhada
title Chromate reductase activity in whole cells and crude cell free extract of Acinetohacter Haemolyticus
title_short Chromate reductase activity in whole cells and crude cell free extract of Acinetohacter Haemolyticus
title_full Chromate reductase activity in whole cells and crude cell free extract of Acinetohacter Haemolyticus
title_fullStr Chromate reductase activity in whole cells and crude cell free extract of Acinetohacter Haemolyticus
title_full_unstemmed Chromate reductase activity in whole cells and crude cell free extract of Acinetohacter Haemolyticus
title_sort chromate reductase activity in whole cells and crude cell free extract of acinetohacter haemolyticus
publishDate 2012
url http://eprints.utm.my/id/eprint/32395/1/NorsuhadaAbdulKarimMFS2012.pdf
http://eprints.utm.my/id/eprint/32395/
http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:68009?site_name=Restricted Repository
_version_ 1643649027069181952
score 13.211869

Similar Items