• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.5
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• pp.294-298
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• 2003

Endocrine-disrupting phenolic compounds in the water were degraded by laccase from Trametes sp. followed by activated sludge treatment. The effect of temperature on the degradation of phenolic compounds and the production of organic compounds were investigated using endocrine-disrupting chemicals such as bisphenol A, 2.4-dichlorophenol, and diethyl phthalate. Bisphenol A and 2.4-dichlorophenol disappeared completely after the laccase treatment, but no disappearance of diethyl phthalate was observed. The Michaelis-Menten type equation was proposed to represent the degradation rate of bisphenol A by the lacasse under various temperatures. After the laccase treatment of endocrine-disrupting chemicals, the activated sludge treatment was attempted and it could convert about 85 and 75% of organic compounds produced from bisphenol A and 2.4-dichlorophenol into H$_2$O and CO$_2$, respectively.

• Journal of Microbiology
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• v.42 no.2
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• pp.94-98
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• 2004

Phenanthrene is a three-ring polycyclic aromatic hydrocarbon and commonly found as a pollutant in various environments. Degradation of phenanthrene by white rot fungus Trametes versicolor 951022 and its laccase, isolated in Korea, was investigated. After 36 h of incubation, about 46％ and 65％ of 100 mg/l of phenanthrene added in shaken and static fungal cultures were removed, respectively. Phenanthrene degradation was maximal at pH 6 and the optimal temperature for phenanthrene removal was 30$^{\circ}C$. Although the removal percentage of phenanthrene was highest (76.7％) at 10 mg/1 of phenanthrene concentration, the transformation rate was maximal (0.82 mg/h) at 100 mg/L of phenanthrene concentration in the fungal culture. When the purified laccase of T. versicolor 951022 reacted with phenanthrene, phenanthrene was not transformed. The addition of redox mediator, 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) or 1-hydroxybenzotriazole (HBT) to the reac-tion mixture increased oxidation of phenanthrene by laccase about 40％ and 30％, respectively.

• Journal of Environmental Health Sciences
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• v.33 no.1 s.94
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• pp.63-67
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• 2007

Laccase catalyzes the oxidation and polymerization of aromatic compounds in the presence of molecular oxygen. The oxidative transformation of chlorophene with laccase was conducted in a closed, temperature controlled system. The optimal pH for transformation of chlorophene was proven to be about 5-6. As the temperature rose up to $55^{\circ}C$, the transformation of chlorophene increased. The chlorophene transformation was not enhanced in the presence of soluble polymers. The toxicity of the reaction mixture was increased two times than that of initial reaction mixture after the enzymatic treatment. ABTS has enhanced chlorophene transformation at 0.1 mM and showed negative linear relationship with residual chlorophene by the reaction.

• Korean Journal of Microbiology
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• v.29 no.4
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• pp.238-242
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• 1991

Extracellular laccase secreted from Pleurotus ostreatus was activated by $Cu^{2+}$ and $Cu^{+}$ . The enzyme was strongly inactivated by 8-hydroxyquinoline, potassium cyanide, sodium azide, sodium bisulfite and 2-mercaptoethanol. The two ionogenic groups, which have pKa values of 5.60-5.70 and 6.70-6.85 respectively, were found to relate with the active site of this enzyme. The oxidation reactions were brought about by initial single electron transfer process on the active site. The enzyme was found to be a metalloprotein which had about 3.9 cupric ions per molecule of protein as a prosthetic group. The enzyme showed a strong peak at 605 nm and a weak shoulder at 330 nm in UV-Visible absorption spectrum. Both signals disappeated upon treatment of the enzyme with 4 electron equivalent ascorbate. These results indicate that type I Cu peak and type III Cu shoulder are present in laccase.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.1
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• pp.1-10
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• 2014

Xylanase (X) derived from Aurreobasidium pullulans and laccase-mediator system (LM) using Trichophyton sp. LKY-7 laccase (TrL) and N-hydroxy-2-pyridone analogue (NHP) as a mediator were applied in hardwood kraft pulp (HwKP) bleaching. The individual and the synergistic effects of X and LM stage were investigated in the enzymatic bleaching of HwKP. Also, the effects of subsequent alkaline extraction (E) and alkaline/hydrogen peroxide treatment (P) were examined. In X or LM treatment alone, an appreciable bleaching effect of HwKP was not observed, whereas subsequent E or P stage enhanced the increase of brightness and the decrease of kappa number. Especially, P stage significantly enhanced the bleaching effect of pulp. Bleaching of HwKP with XLM sequentially gave significantly higher pulp brightness and lower kappa number than that obtained after the treatment of HwKP with X+LM simultaneously. When HwKP was sequentially treated with XLM followed by P stage, the brightness increased by about 11% ISO and the kappa number decreased by about 3.6 in comparison with the initial pulp. Xylanase and laccase were strongly inactivated by NHP both in the absence and the presence of pulp.

• Journal of Microbiology
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• v.37 no.3
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• pp.148-153
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• 1999

Laccase produced by Coriolus hirsutus was purified to electrophoretic homogeneity by acetone precipitation, Sephacryl S-2000 HR chromatography, DEAE Sepharose CL-6B chromatography, and Mono Q HR 5/5 chromatography. The purification of laccase was 46.6-fold with an overall yield of 23.7%. Laccase from this fungus was a monomeric glycoprotein with 16% carbohydrate content, and has an isoelectric point of 4.2, and molecular mass of 78 kDa, respectively. The N-terminal amino acid sequence of the enzyme showed significant homology to hoste of laccases from Coriolus versicolor, Pycnoporus cinnabarius, and an unidentified basidiomycete, PM1. The highest rate of 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) oxidation by laccase was reached at 45$^{\circ}C$, and te pH optima of the enzyme varied depending on the substrate in the range of 2.0 to 4.5. The enzyme was stable at 60$^{\circ}C$ for 5 h and lost 80% activity at 80$^{\circ}C$ in 30 min. The enzyme oxidized a variety of usual laccase substrates including lignin-related phenol, and had the highest affinity toward ABTS. Under standard assay conditions, the apparent Km value of the enzyme toward ABTS was 8.1 ${\mu}$M. The enzyme was completely inhibited by L-cysteine and sodium azide, but not by potassium cyanide, SDS, ad thiourea.

• Journal of Plant Biotechnology
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• v.35 no.1
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• pp.41-45
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• 2008

Laccase (EC 1.10.3.2) is a small group of enzymes that catalyze the oxidation of a broad range of phenolic compounds including hazardous and recalcitrant pollutants in the environment. This study attempted to develop an efficient system for production of a recombinant laccase by chloroplast genetic transformation of tobacco. Chloroplast transformation vector was constructed and introduced into the tobacco chloroplast genome using particle bombardment. Chloroplast-transformed plants were subsequently regenerated. PCR and southern blot analyses confirmed stable integration of the laccase gene into the chloroplast genome. Northern blot analysis revealed that mRNA of the laccase gene was highly expressed in chloroplast-transformed plants.

• Journal of the Korean Wood Science and Technology
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• v.27 no.4
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• pp.72-79
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• 1999

The ability of several wood rotting fungi for decolorization of two anthracene derivatives, Carminic acid (CA) and Remazol brilliant blue R (RBBR), and hardwood KP bleaching liquor (BL) as well as laccase activities in these fungi were studied. The enzyme activity appeared exclusively in fungi destaining RBBR and CA, but in the case of BL, such relationship was not observed. The laccase enzyme was released into the decolorization media and its inducible (but not constitutive) forms shown destaining activity. The purified inducible forms of Kuehneromyces mutabilis and Pleurotus ostreatus laccase destained CA. Thus the possible differentiation between specificity of particular LAC forms was confirmed. In addition the nitrogen starvation induced both laccase and CA destaining activities, but the increase was higher for decolorization of CA than LAC activity. Probably LAC would be only partly responsible for decolorization of this dye. This results suggested that purified LACs decolorize CA, however its destaining activities were considerably lower than the activities on syringaldazine.

• Journal of Microbiology and Biotechnology
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• v.19 no.11
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• pp.1421-1430
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• 2009

With an aim to evaluate dye decolorization by white rot fungus on natural living conditions, reproducing by solid-state fermentation, the process of triphenylmethane dyes decolorization using the white rot fungus P. ostreatus BP, cultivated on rice straw solid-state medium, has been demonstrated. Three typical dyes, including malachite green, bromophenol blue, and crystal violet, were almost completely decolorized by the fungus after 9 days of incubation. During the process of dye decolorization, the activities of enzyme secreted by the fungus, and the contents of soluble components, such as phenolic compounds, protein, and sugar, changed regularly. The fungus could produce ligninolytic, cellulolytic, and hemicellulolytic enzymes and laccase was the most dominant enzyme in solid-state medium. Laccase, laccase isoenzyme, and the laccase mediator could explain the decolorization of malachite green, bromophenol blue, and crystal violet by the fungus in solid-state medium, respectively. It is worth noting that the presence of the water-soluble phenolic compounds could stimulate the growth of fungus, enhance the production of laccase, and accelerate dye decolorization.

• Mycobiology
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• v.42 no.4
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• pp.322-330
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• 2014

The aim of this study was to identify and characterize new Flammulina velutipes laccases from its whole-genome sequence. Of the 15 putative laccase genes detected in the F. velutipes genome, four new laccase genes (fvLac-1, fvLac-2, fvLac3, and fvLac-4) were found to contain four complete copper-binding regions (ten histidine residues and one cysteine residue) and four cysteine residues involved in forming disulfide bridges, fvLac-1, fvLac-2, fvLac3, and fvLac-4, encoding proteins consisting of 516, 518, 515, and 533 amino acid residues, respectively. Potential N-glycosylation sites (Asn-Xaa-Ser/Thr) were identified in the cDNA sequence of fvLac-1 (Asn-454), fvLac-2 (Asn-437 and Asn-455), fvLac-3 (Asn-111 and Asn-237), and fvLac4 (Asn-402 and Asn-457). In addition, the first 19~20 amino acid residues of these proteins were predicted to comprise signal peptides. Laccase activity assays and reverse transcription polymerase chain reaction analyses clearly reveal that $CuSO_4$ affects the induction and the transcription level of these laccase genes.