A High Redox Potential Laccase from Pycnoporus sanguineus RP15: Potential Application for Dye Decolorization

• Main Authors: Ana L. R. L. Zimbardi, Priscila F. Camargo, Sibeli Carli, Sidney Aquino Neto, Luana P. Meleiro, Jose C. Rosa, Adalgisa R. De Andrade, João A. Jorge, Rosa P. M. Furriel
• Format: Article
• Language: English
• Published: MDPI AG 2016-05-01
• Series: International Journal of Molecular Sciences
• Subjects: Pycnoporus sanguineus; solid state fermentation; response surface methodology; laccase; purification; characterization; decolorization; remazol brilliant blue R; Reactive blue 4; bromophenol blue
• Online Access: http://www.mdpi.com/1422-0067/17/5/672

Laccase production by Pycnoporus sanguineus RP15 grown in wheat bran and corncob under solid-state fermentation was optimized by response surface methodology using a Central Composite Rotational Design. A laccase (Lacps1) was purified and characterized and the potential of the pure Lacps1 and the crude culture extract for synthetic dye decolorization was evaluated. At optimal conditions (eight days, 26 °C, 18% (w/w) milled corncob, 0.8% (w/w) NH4Cl and 50 mmol·L−1 CuSO4, initial moisture 4.1 mL·g−1), the laccase activity reached 138.6 ± 13.2 U·g−1. Lacps1 was a monomeric glycoprotein (67 kDa, 24% carbohydrate). Optimum pH and temperature for the oxidation of 2,2’-azino-bis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) were 4.4 and 74.4 °C, respectively. Lacps1 was stable at pH 3.0–8.0, and after two hours at 55–60 °C, presenting high redox potential (0.747 V vs. NHE). ABTS was oxidized with an apparent affinity constant of 147.0 ± 6.4 μmol·L−1, maximum velocity of 413.4 ± 21.2 U·mg−1 and catalytic efficiency of 3140.1 ± 149.6 L·mmol−1·s−1. The maximum decolorization percentages of bromophenol blue (BPB), remazol brilliant blue R and reactive blue 4 (RB4), at 25 or 40 °C without redox mediators, reached 90%, 80% and 60%, respectively, using either pure Lacps1 or the crude extract. This is the first study of the decolorization of BPB and RB4 by a P. sanguineus laccase. The data suggested good potential for treatment of industrial dye-containing effluents.