Purification and partial characterization of azoreductase from Enterobacter agglomerans

Moutaouakkil, Adnane; Zeroual, Youssef; Dzayri, Fatima Zohra; Talbi, Mohamed; Lee, Kangmin; Blaghen, Mohamed

doi:10.1016/s0003-9861(03)00096-1

Cited by 113 publications

(71 citation statements)

References 25 publications

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“…The application of affinity chromatography for the purification of azoreductase has previously been described (24,25,33,39). Compared to previous reports (25), for which a 55-fold purification was achieved with this technique, only a 5-fold purification was calculated for the azoreductase from Bacillus strain SF, probably due to denaturation and/or irreversible adsorption of the enzyme in the Cibacron Blue F3G-A column.…”

Section: Discussionmentioning

confidence: 93%

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A New Alkali-Thermostable Azoreductase from Bacillus sp. Strain SF

Maier

Kandelbauer

Erlacher

et al. 2004

Appl Environ Microbiol

216

100

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A screening for dye-decolorizing alkali-thermophilic microorganisms resulted in a Bacillus sp. strain isolated out of the wastewater drain of a textile finishing company. An NADH-dependent azoreductase of this strain, Bacillus sp. strain SF, was found to be responsible for the decolorization of azo dyes. This enzyme was purified by a combination of ammonium sulfate precipitation and anion-exchange and affinity chromatography and had a molecular mass of 61.6 kDa and an isoelectric point at pH 5.3. The pH optimum of the azoreductase depended on the substrate and was within the range of pHs 8 to 9, while the temperature maximum was reached at 80°C. Decolorization only took place in the absence of oxygen and was enhanced by FAD, which was not consumed during the reaction. A 26% similarity of this azoreductase to chaperonin Cpn60 from a Bacillus sp. was found by peptide mass mapping experiments. Substrate specificities of the azoreductase were studied by using synthesized model substrates based on di-sodium-(R)-benzyl-azo-2,7-dihydroxy-3,6-disulfonyl-naphthaline. Those dyes with NO 2 substituents, especially in the ortho position, were degraded fastest, while analogues with a methyl substitution showed the lowest degradation rates.In the last few years, environmental legislation, e.g., about the appearance of color in discharges, combined with the increasing cost of water for the industrial sector, has made the treatment and reuse of dyeing effluents increasingly attractive to the industry. The common method for the treatment of wastewater in the textile finishing industry is physicochemical flocculation in combination with biological treatment (17). The conventional treatment of colored effluents produces a lot of sludge, but does not remove all dyes, thus preventing recycling of the treated wastewater. In activated sludge treatments, dyeing effluents, e.g., reactive azo dyes and naphthaline-sulfonic acids as well as aromatic amino derivatives, represent an extensive nonbiodegradable class of compounds (18) and can even inhibit activated sludge organisms. Thus, the development of more effective biological systems for the treatment of these types of wastewater has resulted in considerable interest by the industry.Wood-rotting fungi (e.g., Phanerochaete chrysosporium, Trametes sp., and Aspergillus sp.) have been found to effectively degrade a variety of azo dyes under aerobic conditions (16). Dye-degrading fungi have been used frequently in bioreactors for the decolorization and degradation of azo dyes (37). While fungal treatment of effluents is usually very time-consuming (3), immobilized enzymes could have potential for dye decolorization and recycling of effluents (1) without the need for the addition of growth substrates. The enzymes involved in the degradation of azo dyes are mainly peroxidases (12) and laccases (1). However, a significant cost reduction for these enzymes would be required in order to make this process economically more attractive. Aerobic bacteria have been described to oxidatively decolorize m...

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Section: Discussionmentioning

confidence: 93%

“…Previously, molecular masses of 21 and 30 kDa were reported for azoreductases from Pseudomonas sp. (38,39) and a mass of 28 kDa was reported for Enterobacter agglomerans (24). Temperature optima for azoreductases reported in the literature range from 40 to 45°C (15,22).…”

Section: Discussionmentioning

confidence: 95%

A New Alkali-Thermostable Azoreductase from Bacillus sp. Strain SF

Maier

Kandelbauer

Erlacher

et al. 2004

Appl Environ Microbiol

216

100

View full text Add to dashboard Cite

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“…Many kinds of bacterial azoreductases have been isolated and characterized for the progress of bioremediation (7)(8)(9)(10)(11)(12)(13)(14)(15). However, AzoR is different from other azoreductases reported thus far with respect to its requirements for cofactors, electron donors, and substrate specificity and its amino acid sequence.…”

mentioning

confidence: 99%

Three-dimensional Structure of AzoR from Escherichia coli

Ito

Nakanishi

Lee

et al. 2006

Journal of Biological Chemistry

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The crystal structure of AzoR (azoreductase) has been determined in complex with FMN for two different crystal forms at 1.8 and 2.2 Å resolution. AzoR is an oxidoreductase isolated from Escherichia coli as a protein responsible for the degradation of azo compounds. This enzyme is an FMN-dependent NADH-azoreductase and catalyzes the reductive cleavage of azo groups by a ping-pong mechanism. The structure suggests that AzoR acts in a homodimeric state forming the two identical catalytic sites to which both monomers contribute. The structure revealed that each monomer of AzoR has a flavodoxin-like structure, without the explicit overall amino acid sequence homology. Superposition of the structures from the two different crystal forms revealed the conformational change and suggested a mechanism for accommodating substrates of different size. Furthermore, comparison of the active site structure with that of NQO1 complexed with substrates provides clues to the possible substrate-binding mechanism of AzoR.

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“…Certaines de ces bactéries, telles que Enterobacter agglomerans (MoUTAoUAkkIL et al, 2003;MoUTAoUAkkIL et al, 2004) D'autres sont capables d'utiliser les amines aromatiques formées comme sources uniques de carbone, aboutissant ainsi à une dégradation complète ou « minéralisation » des colorants azoïques. Ces bactéries dégradent les molécules colorantes par la succession de deux étapes enzymatiques : une azoréduction, non sensible à l'oxygène, suivie d'une métabolisation à oxygène dépendant (BLüMEL et al, 1998;WoNG et yUEN, 1998).…”

Section: Décoloration Par Les Bactériesunclassified

Les colorants textiles sources de contamination de l’eau : CRIBLAGE de la toxicité et des méthodes de traitement

Mansour¹,

Boughzala

Dridi

et al. 2011

rseau

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Les colorants sont largement utilisés dans les imprimeries, les produits alimentaires, cosmétiques et cliniques, mais en particulier dans les industries textiles pour leur stabilité chimique et la facilité de leur synthèse et leur variété de couleurs. Cependant, ces colorants sont à l’origine de la pollution une fois évacués dans l’environnement. La production mondiale des colorants est estimée à plus de 800 000 t•an-1 et les colorants azoïques sont majoritaires et représentent 60-70 %. Compte tenu de la composition très hétérogène de ces derniers, leur dégradation conduit souvent à la conception d’une chaîne de traitement physique-chimique et biologique assurant l’élimination des différents polluants par étapes successives. Dés études ont montré que plusieurs colorants azoïques sont toxiques et mutagènes et le traitement biologique de ces colorants semble présenter un intérêt scientifique majeur. Les traitements physico-chimiques communs (adsorption, coagulation/floculation, précipitation etc.) sont couramment utilisés pour les effluents industriels. Malgré leur rapidité, ces méthodes se sont avérées peu efficaces compte tenu des normes exigées sur ces rejets. Le traitement biologique constitue une alternative fiable; en effet, plusieurs microorganismes sont capables de transformer les colorants azoïques en sous-produits incolores. Les bactéries dégradent les colorants azoïques en deux étapes : un clivage de liaison azo, par l’intermédiaire de l’azoréductase, suivi d’une oxydation des amines aromatiques formées lors de la première étape. L’azoréduction constitue alors une étape clé du traitement des effluents chargés de ces colorants.Dyes are widely used for industrial, printing, food, cosmetic and clinical purposes as well as textile dyeing because of their chemical stability, ease of synthesis, and versatility. Their stability, however, causes pollution once the dyes are released into the environment in effluents. More than 800,000 tons of dyes are annually produced worldwide, of which 60 to 70% are azo dyes. Considering the heterogeneous composition of these latter dyes, their degradation usually requires a chain of physical, chemical and biological treatments assuring the elimination of different pollutants in successive steps. In addition, some azo dyes are toxic and mutagenic and thus the biological treatment of these dyes is now of major scientific interest. Physical-chemical treatments (adsorption, coagulation/flocculation precipitation, etc.) are usually used for industrial effluents. In spite of their rapidity, these methods have turned out to be ineffective in attaining the standards required for these discharges. As a viable alternative, biological processes are receiving increasing interest owing to their cost effectiveness and their ability to produce less sludge. It has been found that some microorganisms can transform azo dyes into colourless products. Bacterial degradation of azo dyes is often initiated by an enzymatic biotransformation step that involves cleavage of azo linkages with the aid of...

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Purification and partial characterization of azoreductase from Enterobacter agglomerans

Cited by 113 publications

References 25 publications

A New Alkali-Thermostable Azoreductase from Bacillus sp. Strain SF

A New Alkali-Thermostable Azoreductase from Bacillus sp. Strain SF

Three-dimensional Structure of AzoR from Escherichia coli

Les colorants textiles sources de contamination de l’eau : CRIBLAGE de la toxicité et des méthodes de traitement

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