Purification and characterization of lignin peroxidase from white-rot fungi Pleurotus pulmonarius CPG6 and its application in decolorization of synthetic textile dyes

Abstract

From the biotechnological point of view, enzymes are powerful tools that help sustain a clean environment in several ways. The enzymatic biodegradation of synthetic dyes is a promising goal since it reduces pollution caused by textile dyeing factory wastewa-ter. Lignin peroxidase (EC 1.11.1.14, LiP) has high redox potential; thus, it is great for application in various industrial fields (e.g., paper-waste treatment and textile dyeing wastewater treatment). In the present study, a LiP from an isolated strain Pleurotus pulmonarius CPG6 (PpuLiP) was success-fully purified with a specific activity of 6.59 U mg-1. The enzyme was purified by using three-step column chromatography procedures including DEAE, Sep-hadex G-75, and HiTrap™ Q FF columns with 17.8-fold purity. The enzyme with a molecular weight of 40 kDa exhibited enhanced pH stability in the acidic range. The activity retention was over 75% at a pH of 3.0 for more than 6 hours. Purified PpuLiP was able to oxidize a variety of substrates including ver-atryl alcohol, 2,4-DCP, n-propanol, and guaiacol. The effect of metal ions on PpuLiP activity was ana-lyzed. The study will provide a ground to decolorize dyes from various groups of PpuLiP. Purified PpuLiP could decolorize 35% Acid blue 25 (AB25), 50% Acid red 129 (AB129), 72% Acid blue 62 (NY3), 85% Acid blue 113 (AB113), 55% Remazol Brilliant blue R (RBBR), and 100% Reactive red 120 (RR120) for 12 hours. Most of the dyes were decolorized, but the heat-denatured enzyme used as negative control obviously did not decolorize the tested dyes. These results indicate that the PpuLiP has potential application in enzyme-based decolorization of synthetic dyes.