Reduction of azo dyes by flavin reductase from Citrobacter freundii A1

  • Mohd Firdaus Abdul-Wahab Department of Biological Sciences, Faculty of Biosciences and Bioengineering; Nanoporous and Mesoporous Materials for Biological Applications Research Group (NAMBAR), Sustainability Research Alliance, Malaysia.
  • Giek Far Chan Department of Biological Sciences, Faculty of Biosciences and Bioengineering; Nanoporous and Mesoporous Materials for Biological Applications Research Group (NAMBAR), Sustainability Research Alliance, Malaysia.
  • Abdull Rahim Mohd Yusoff Institute of Environmental and Water Resource Management, Water Research Alliance, Universiti Technologi Malaysia, Johor, Malaysia.
  • Noor Aini Abdul Rashid | nooraini_nar@fbb.utm.my Department of Biological Sciences, Faculty of Biosciences and Bioengineering; Nanoporous and Mesoporous Materials for Biological Applications Research Group (NAMBAR), Sustainability Research Alliance, Malaysia.

Abstract

Citrobacter freundii A1 isolated from a sewage treatment facility was demonstrated to be able to effectively decolorize azo dyes as pure and mixed culture. This study reports on the investigation on the enzymatic systems involved. An assay performed suggested the possible involvement of flavin reductase (Fre) as an azo reductase. A heterologouslyexpressed recombinant Fre from C. freundii A1 was used to investigate its involvement in the azo reduction process. Three model dyes were used, namely Acid Red 27 (AR27), Direct Blue 15 (DB15) and Reactive Black 5 (RB5). AR27 was found to be reduced the fastest by Fre, followed by RB5, and lastly DB15. Redox mediators nicotinamide adenine dinucleotide (NADH) and riboflavin enhance the reduction, suggesting the redox activity of the enzyme. The rate and extent of reduction of the model dyes correlate well with the reduction potentials (Ep). The data presented here strongly suggest that Fre is one of the enzymes responsible for azo reduction in C. freundii A1, acting via an oxidation-reduction reaction.

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Published
2012-12-18
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Original Articles
Supporting Agencies
Ministry of Science, Technology and Innovation Malaysia (MOSTI) Malaysia, Universiti Teknologi Malaysia
Keywords:
azo dyes, flavin reductase, azoreductase, redox system, C. freundii A1.
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How to Cite
Abdul-Wahab, M. F., Chan, G. F., Mohd Yusoff, A. R., & Abdul Rashid, N. A. (2012). Reduction of azo dyes by flavin reductase from Citrobacter freundii A1. Journal of Xenobiotics, 3(1), e2. https://doi.org/10.4081/xeno.2013.e2