Characterization of Two Hydrogen Peroxide Resistant Peroxidases from Rhodococcus opacus 1CP

Abstract

The dye-decolorizing peroxidases (DyP) are a family of heme-dependent enzymes present on a broad spectrum of microorganisms. While the natural function of these enzymes is not fully understood, their capacity to degrade highly contaminant pigments such as azo dyes or anthraquinones make them excellent candidates for applications in bioremediation and organic synthesis. In this work, two novel DyP peroxidases from the organism Rhodococcus opacus 1CP (DypA and DypB) were cloned and expressed in Escherichia coli. The enzymes were purified and biochemically characterized. The activities of the two DyPs via 2,2′-azino-bis [3-ethylbenzthiazoline-6-sulphonic acid] (ABTS) assay and against Reactive Blue 5 were assessed and optimized. Results showed varying trends for DypA and DypB. Remarkably, these enzymes presented a particularly high tolerance towards H2O2, retaining its activities at about 10 mM H2O2 for DypA and about 4.9 mM H2O2 for DypB.

Microbial Degradation of Azo Dyes: Approaches and Prospects for a Hazard-Free Conversion by Microorganisms

“…There are several enzymes that have been found to reduce and degrade dyes. Some of the best-known enzymes are manganese peroxidases [156][157][158], lignin peroxidases [103,111,159], laccases [111,160], dye peroxidases [161,162], and azoreductases [163][164][165][166], all of which will be introduced in this section.…”

“…These enzymes were discovered to attack azo dyes and the anthraquinone skeleton and hence earned the name dye-decolorizing peroxidases [177]. They contain the highly conserved GXXDG motif in their primary sequences and in addition a conserved Asp, a distal Arg, and a proximal His, which are important for stability, heme-binding, and biocatalysis [162,178,179]. DyPs can be classified into four types (A-D), where types A to C are widespread in bacteria and type D is of fungal origin [180,181].…”

Process optimization for efficacious biodecolorization of crystal violet by Malaysian Rhodococcus pyridinivorans using monothetic analysis

“…Shaking condition allowed seamless transfer of oxygen between the cells and medium, leading to increased cell concentration [16] which suited the function of R. pyridinivorans as an aerobic bacterium. Under agitated mode, primary enzymes such as lignin peroxidase and manganese through oxidative reactions may largely contribute to higher decolorization of crystal violet [16] as Rhodococcus strains were known to possess these enzymes [18][19][20]. On the contrary, the decolorization of crystal violet by Aspergillus niger was established at static condition which may be caused by the presence of azoreductase [2].…”