Cloning and characterization of a Flavin-free oxygen-insensitive azoreductase from Klebsiella oxytoca GS-4-08
This study reports the identification of a new bacterial azoreductase (AzoR) from Klebsiella oxytoca GS-4-08, its heterologous production in Escherichia coli and the decolorization of azo dyes.
The AzoR, as a flavin-free, oxygen-insensitive enzyme, has a molecular mass of 22 kDa and a high substrate specificity for methyl red (MR). In the presence of 5 mM of NADH, the enzyme activity for decolorization of 50 mg l−1 of MR reached 5.61 μmol min−1 mg protein−1. Double-reciprocal plots indicated that the NADH and MR reductions proceed by ping-pong mechanism. The calculated Vm was 8.17 μM min−1 mg protein−1, and the AzoR retained over 75% of relative activity under temperature range from 20 to 50 °C.
This study for the first time identified an AzoR from Klebsiella oxytoca strain, which enabled efficient degradation of azo dyes by strain GS-4-08.
KeywordsAzoreductase Flavin Klebsiella oxytoca Oxygen-insensitive
This research was supported by the National Natural Science Foundation of China (No. 51778298) and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).
Compliance with ethical standards
Conflict of interest
The Authors declare that there is no conflict of interest.
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