Enhanced transformation of malachite green by laccase of Ganoderma lucidum in the presence of natural phenolic compounds.
In this study, we investigated the efficacy of phenolic extract of wheat bran and lignin-related phenolic compounds as natural redox mediators on laccase-mediated transformation of malachite green (MG) using purified laccase from the white-rot fungus Ganoderma lucidum. G. lucidum laccase was able to decolorize 40.7% MG dye (at 25 mg l(-1)) after 24 h of incubation. Whereas, the addition of phenolic extract of wheat bran enhanced the decolorization significantly (p<0.001) by two- to threefold than that of purified laccase alone. Among various natural phenolic compounds, acetovanillone, p-coumaric acid, ferulic acid, syringaldehyde, and vanillin were the most efficient mediators, as effective as the synthetic mediator 1-hydroxybenzotriazole. Characterization of MG transformation products by HPLC, UV-Vis, and liquid chromatography-mass spectrometry-electrospray ionization analysis revealed that N-demethylation was the key mechanism of decolorization of MG by laccase. Growth inhibition test based on mycelial growth inhibition of white rot fungus Phanerochaete chrysosporium revealed that treatment with laccase plus natural mediators effectively reduced the growth inhibitory levels of MG than that of untreated one. Among all the tested compounds, syringaldehyde showed the highest enhanced decolorization, as a consequence reduced growth inhibition was observed in syringaldehyde-treated samples. The results of the present study revealed that the natural phenolic compounds could alternatively be used as potential redox mediators for effective laccase-mediated decolorization of MG.
Murugesan
Kumarasamy
K
School of Environmental Science and Engineering, POSTECH, San 31, Hyoja-dong, Nam-gu, Pohang 790-784, South Korea.
Yang
In-Hee
IH
Kim
Young-Mo
YM
Jeon
Jong-Rok
JR
Chang
Yoon-Seok
YS
D001711:Biotransformation; D004396:Coloring Agents / Q000737:chemistry* / Q000378:metabolism; D004043:Dietary Fiber / Q000032:analysis; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D042845:Laccase / Q000235:genetics / Q000378:metabolism*; D020075:Phanerochaete / Q000254:growth & development; D010636:Phenols / Q000737:chemistry* / Q000378:metabolism; D010936:Plant Extracts / Q000737:chemistry / Q000378:metabolism; D020940:Reishi / Q000201:enzymology*; D012394:Rosaniline Dyes / Q000737:chemistry* / Q000378:metabolism
D004396:Coloring Agents; D004043:Dietary Fiber; D005656:Fungal Proteins; D010636:Phenols; D010936:Plant Extracts; D012394:Rosaniline Dyes; C005095:malachite green; D042845:Laccase