Synergistic effect of laccase mediators on pentachlorophenol removal by Ganoderma lucidum laccase |
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Authors: | Jong-Rok Jeon Kumarasamy Murugesan Young-Mo Kim Eun-Ju Kim Yoon-Seok Chang |
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Institution: | (1) School of Environmental Science and Engineering, POSTECH, Pohang, 790-784, South Korea |
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Abstract: | Laccases have low redox potentials limiting their environmental and industrial applications. The use of laccase mediators
has proven to be an effective approach for overcoming the low redox potentials. However, knowledge about the role played by
the mediator cocktails in such a laccase-mediator system (LMS) is scarce. Here, we assembled different dual-agent mediator
cocktails containing 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS), vanillin, and/or acetovanillone, and compared
their mediating capabilities with those of each individual mediator alone in oxidation of pentachlorophenol (PCP) by Ganoderma lucidum laccase. Cocktails containing ABTS and either vanillin or acetovanillone strongly promoted PCP removal compared to the use
of each mediator alone. The removal enhancement was correlated with mediator molar ratios of the cocktails and incubation
times. Analysis of the kinetic constants for each mediator compound showed that G. lucidum laccase was very prone to react with ABTS rather than vanillin and acetovanillone in the cocktails. Moreover, the presence
of the ABTS radical (ABTS+•) and vanillin or acetovanillone significantly enhanced PCP removal concomitant with electron transfer from vanillin or acetovanillone
to ABTS+•. These results strongly suggest that vanillin and acetovanillone mediate the reaction between ABTS and PCP via multiple sequential
electron transfers among laccase and its mediators. |
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Keywords: | Laccase-mediator system Ganoderma lucidum laccase Pentachlorophenol |
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