title: Laccase-catalyzed decolorization of malachite green: performance optimization and degradation mechanism.
abstract: Malachite green (MG) was decolorized by laccase (LacA) of white-rot fungus Cerrena sp. with strong decolorizing ability. Decolorization conditions were optimized with response surface methodology. A highly significant quadratic model was developed to investigate MG decolorization with LacA, and the maximum MG decolorization ratio of 91.6% was predicted under the conditions of 2.8 U mL(-1) LacA, 109.9 mg L(-1) MG and decolorization for 172.4 min. Kinetic studies revealed the Km and kcat values of LacA toward MG were 781.9 mM and 9.5 s(-1), respectively. UV-visible spectra confirmed degradation of MG, and the degradation mechanism was explored with liquid chromatography-mass spectrometry (LC-MS) analysis. Based on the LC-MS spectra of degradation products, LacA catalyzed MG degradation via two simultaneous pathways. In addition, the phytotoxicity of MG, in terms of inhibition on seed germination and seedling root elongation of Nicotiana tabacum and Lactuca sativa, was reduced after laccase treatment. These results suggest that laccase of Cerrena was effective in decolorizing MG and promising in bioremediation of wastewater in food and aquaculture industries.
authors.affiliation: College of Biological Sciences and Technology, Fuzhou University, Fuzhou, Fujian, China; Fujian Key Laboratory of Marine Enzyme Engineering, Fuzhou, Fujian, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Yang
authors.affiliation: College of Biological Sciences and Technology, Fuzhou University, Fuzhou, Fujian, China; Fujian Key Laboratory of Marine Enzyme Engineering, Fuzhou, Fujian, China.
authors.forename: Xiaodan
authors.initials: X
authors.lastname: Yang
authors.affiliation: Technical Center, Fujian Entry-Exit Inspection and Quarantine Bureau, Fuzhou, Fujian, China.
authors.forename: Yonghui
authors.initials: Y
authors.lastname: Lin
authors.affiliation: School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Tzi Bun
authors.initials: TB
authors.lastname: Ng
authors.affiliation: College of Biological Sciences and Technology, Fuzhou University, Fuzhou, Fujian, China; Fujian Key Laboratory of Marine Enzyme Engineering, Fuzhou, Fujian, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Lin
authors.affiliation: College of Biological Sciences and Technology, Fuzhou University, Fuzhou, Fujian, China; Fujian Key Laboratory of Marine Enzyme Engineering, Fuzhou, Fujian, China.
authors.forename: Xiuyun
authors.initials: X
authors.lastname: Ye
mesh_terms: D001487:Basidiomycota / Q000201:enzymology*; D005656:Fungal Proteins / Q000737:chemistry*; D042845:Laccase / Q000737:chemistry*; D018545:Lactuca / Q000254:growth & development; D018517:Plant Roots / Q000254:growth & development; D012394:Rosaniline Dyes / Q000737:chemistry*; D036226:Seedlings / Q000254:growth & development; D014026:Nicotiana / Q000254:growth & development; D062065:Wastewater / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D005656:Fungal Proteins; D042845:Laccase; D012394:Rosaniline Dyes; D062065:Wastewater; C005095:malachite green