Mediator-assisted decolorization and detoxification of textile dyes/dye mixture by Cyathus bulleri laccase.
Laccase from basidiomycete fungus Cyathus bulleri was evaluated for its ability to decolorize a number of reactive and acidic dyes in the presence of natural and synthetic mediators. The extent of decolorization was monitored at different mediator/dye concentrations and incubation time. Among the synthetic mediators, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) was effective at low mediator/dye ratios and resulted in 80-95% decolorization at rates that varied from 226 +/- 4 nmol min(-1) mg(-1) for Reactive Orange 1 to 1,333 +/- 15 nmol min(-1) mg(-1) for Reactive Red 198. Other synthetic mediators like 1-hydroxybenzotriazole and violuric acid showed both concentration- and time-dependent increases in percent decolorization. Natural mediators like vanillin, on the other hand, were found to be less effective on all the dyes except Reactive Orange 1. Computed rates of decolorization were about twofold lower than that with ABTS. The laccase-ABTS system also led to nearly 80% decolorization for the simulated dye mixture. No clear correlation between laccase activity on the mediator and its ability to decolorize dyes was found, but pH had a significant effect: Optimum pH for decolorization coincided with the optimum pH for mediator oxidation. The treated samples were also evaluated for toxicity in model microbial systems. The laccase-mediator system appears promising for treatment of textile wastewaters.
Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, Hauz-Khas, New Delhi, India.
Meenu
M
Chhabra
Saroj
S
Mishra
T R
TR
Sreekrishnan
D001391:Azo Compounds / Q000737:chemistry*; D001463:Barbiturates / Q000494:pharmacology; D001547:Benzaldehydes / Q000494:pharmacology; D052160:Benzothiazoles / Q000494:pharmacology*; D003116:Color; D004396:Coloring Agents / Q000737:chemistry* / Q000633:toxicity; D055365:Cyathus / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D042845:Laccase / Q000378:metabolism*; D009152:Mutagenicity Tests; D009282:Naphthalenesulfonates / Q000737:chemistry*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects; D016958:Pseudomonas putida / Q000187:drug effects; D013451:Sulfonic Acids / Q000494:pharmacology*; D013463:Sulfuric Acid Esters / Q000737:chemistry*; D013783:Textile Industry; D014227:Triazines / Q000737:chemistry*; D014230:Triazoles / Q000494:pharmacology; D014874:Water Pollutants, Chemical / Q000737:chemistry
D001391:Azo Compounds; D001463:Barbiturates; D001547:Benzaldehydes; D052160:Benzothiazoles; D004396:Coloring Agents; D007220:Industrial Waste; D009282:Naphthalenesulfonates; D013451:Sulfonic Acids; D013463:Sulfuric Acid Esters; D014227:Triazines; D014230:Triazoles; D014874:Water Pollutants, Chemical; C094277:violuric acid; C109260:reactive orange; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; C514337:reactive red 198; C011852:1-hydroxybenzotriazole; C100058:vanillin; D042845:Laccase