• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.35 no.5
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• pp.80-86
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• 2003

The wood-degrading fungus Trichophyton sp. LKY-7 (T. LKY-7) was immobilized in ca-alginate beads for laccase production and PCP bioremediation. The immobilized T. LKY-7 enabled the repeated use of this fungus for laccase production and produced high amount of laccase throughout 5 cycles incubation. As a laccase inducer. oak wood meal (Quercus variabilis) seemed to be effective laccase inducer for T. LKY-7, and the optimum addition amount was 1％ (W/W) in glucose-peptone medium. Bioremediation of pentachlorophenol by the immobilized T. LKY-7 reached an efficency of up to 90％ without toxic inhibition. The immobilized T. LKY-7 might thus be applicable for semicontinuous laccase production and bioremediation to serve inoculum for reactor system.

• Microbiology and Biotechnology Letters
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• v.13 no.1
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• pp.65-70
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• 1985

The production media, partial purification and the enzymatic characteristics of laccase from Pleurotus ostreatus were investigated. Among various media tried the double strength onion media showed much higher production of laccase compared to glucose and/or CMC added media. The laccase from Pleurotus ostreatus has the optimum pH of 5.94 for the activity and appears to be stable at relatively broad pH spectrum (4.7-8.7). The experiments on the temperature stability shows that above 90% activity could be preserved after holding at $30^{\circ}C$ for 40 min., 60% activity was remained after 40 min. at $50^{\circ}C$. The Km value of the laccase from Pleurotus ostreatus was estimated to be 3.209mM and the molecular weight of laccase was estimated to be 55,000 by SDS-Polyacrylamide gel electrophoresis.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.34 no.2
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• pp.67-72
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• 2002

The two stage laccase-assisted delignification process led to significant lignin removal in the non-pressurized treatments. It is clearly shown that an alkaline extraction prior to the second laccase treatment significantly increased the overall delignification by ∼15%. This is in line with the contention that the residual lignin has undergone structural changes during the alkaline extraction, and the resulting modified structures are susceptible to the laccase oxidation. In phenolic hydroxyl group, the pre- methylated sample was very responsive to the delignification process. The phenolic hydroxyl groups could be increased during side chain cleavage catalyzed by laccase. This finding demonstrates that the delignification oi etherified structures is an important reaction in the delignificaton by laccase.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2003.04a
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• pp.180-187
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• 2003

The lignin-degrading fungus Trichophyton sp. LKY-7 was immobilized in ca-alginate beads for laccase production and PCP remediation. The immobilized Trichopphyton sp. LKY-7 enabled the repeated use of this fungus for laccase production and produced high amount of laccase throughout 5 cycles incubation. As a laccase inducer oak wood meal(Quercus variabilis) seemed to be effective laccase inducer for Trichophyton sp. LKY-7, and the optimum addition amount was 1%(W/W) in glucose-peptone medium. Biotransformation of pentachlorophenol by immobilized Trichophyton sp. LKY-7 reached an efficency of up to 90% without toxic inhibition. Immobilized Trichophyton sp. LKY-7 might thus be applicable for semicontinuous laccase production and bioremediation to serve inoculum for reactor system.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.29 no.4
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• pp.64-72
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• 1997

백색부후균에 의한 리그닌의 분해양상을 검토하기 위해 리그닌 분해능이 우수하고 laccase활성이 높은 LKY-7 및 C. versicolor-13 균주와 manganese peroxidase 활성은 비교적 높으나 laccase활성이 전혀 나타나지 않는 LSK-27 균주로 lignosulfonate를 처리하였다. LKY-7 과 C. versicolor-13 균주에서는 lignosulfonate의 중합화 현상이 관찰되었으며 중합화는 laccase 활성 과 비례하는 것으로 나타났다. LSK-27 균주에서는 lignosulfonate의 고분자 영역이 분해되면서 탈중합화가 일어났으며 리그닌 분해 효소로는 manganese peroxidase만 검출되었다. 보조기질로 glucose를 첨가한 결과, LKY-7 균주에서는 laccase 활정이 각소하면서 중합화 현상이 어느 정도 감소하였으나 C. versicolor-13 균주는 laccase 활성의 증가와 함께 중합화도 촉진되는 것으로 나타났다. 또한 LSK-27 균주에서도 glucose 첨가에 의해 manganese peroxidase 활성이 증가되면서 lignosulfonate의 중합화가 관찰되었다. lignosulfonate 중합화에는 laccase 뿐만 아니라 manganese peroxidase도 관여하며 보조기질로서 탄소원의 종류도 영향을 미칠것으로 검토되었다.

• Microbiology and Biotechnology Letters
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• v.14 no.2
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• pp.139-143
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• 1986

The production media and enzymatic characteristics of laccase from Ganoderma lucidum was investigated. Potato dextrose yeast extract media was proved to be the best for laccase production. The enzyme has optimum pH of 6.45km value of 6.71 mM and appeared to be stable at wide pH range. The enzyme was inactivated partially by methanol and ethanol and totally by sodium azide but not at all by acetone. Also the enzyme purification was performed and the data is given.

• Journal of the Korean Wood Science and Technology
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• v.48 no.3
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• pp.326-344
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• 2020

Laccase was applied to improve the drying speed of urushi lacquer to confirm a potential use of laccase as an enzyme additive. As a result of applying laccase of lacquer and white-rot fungi, drying times for both Korean and Chinese specimens were reduced. All of the specimens to which laccase was applied were dried(set to touch) within 60 minutes from the start of the drying, and the drying rate was improved as the content ratio of laccase increased. In addition, although there were differences in hardening drying time between Korean and Chinese lacquers, it was confirmed that hardening drying took place even at room with temperature of 20 ± 2 ℃ and humidity of 55-60%. As a result of lacquer layer analysis of the dried specimens, the drying speed was improved when the content ratio of laccase to urushiol was 5:1, and there were no differences in chromaticity and adhesion, confirmed that the layers were stable. It was observed that the gloss of both Korean and Chinese lacquers were reduced when laccase was applied. However, according to the analysis of FT-IR and Py-GC/MS, the changes in components were not as sufficient to affect the physical properties. Thus, its applicability as an additive was confirmed.

• Korean Journal of Microbiology
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• v.52 no.3
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• pp.249-253
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• 2016

The inky cap, Coprinellus congregatus, produces several laccase isozymes during its life cycle: both hyphal tip laccase and sclerotial laccase are involved in the fungal development. When this fungus was transferred to an acid liquid medium (pH 4.0-4.5), a new laccase was synthesized and secreted into the culture supernatant. In order to examine its regulation by external pH, green fluorescent protein gene was ligated at the downstream of the promoters having different lengths. These expression vectors having different promoter lengths were inserted into the fungal transformation vector, pBARGEM7-1. These expression vectors were introduced to the mating type a1 and a2 monokaryons, and the transformants were selected by the phosphinothricin resistance. Transformant a1 (a1TF) and transformant a2 (a2TF) were mated with each other to generate homozygotic dikaryon transformants. All these transformants were grown in neutral liquid medium for 5 days, and then the whole cell homogenates were transferred to the acidic liquid medium (pH 4.1). After 36 h incubation at $25^{\circ}C$, cells were harvested for the analysis of GFP expression. GFP expression was detected in the transformant having full-length promoter (2.0 kb), but other transformants having shorter length promoter (shorter than 1.29 kb) failed to show the fluorescence. Therefore, the acid-responsive element in the laccase promoter should be localized between -2.0 kb ~ -1.29 kb region.

• Journal of Microbiology and Biotechnology
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• v.25 no.8
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• pp.1361-1370
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• 2015

A blue laccase was purified from a white rot fungus of Trametes trogii, which was a monomeric protein of 64 kDa as determined by SDS-PAGE. The enzyme acted optimally at a pH of 2.2 to 4.5 and a temperature of 70℃ and showed high thermal stability, with a half-life of 1.6 h at 60℃. A broad range of substrates, including the non-phenolic azo dye methyl red, was oxidized by the laccase, and the laccase exhibited high affinity towards ABTS and syringaldazine. Moreover, the laccase was fairly metal-tolerant. A high-molecular-weight kraft lignin was effectively polymerized by the laccase, with a maximum of 6.4-fold increase in weight-average molecular weight, as demonstrated by gel permeation chromatography. Notable structural changes in the polymerized lignin were detected by Fourier transform infrared spectroscopy and ¹H NMR spectroscopy. This revealed an increase in condensed structures as well as carbonyl and aliphatic hydroxyl groups. Simultaneously, phenolic hydroxyl and methoxy groups decreased. These results suggested the potential use of the laccase in lignin modification.

• Korean Journal of Microbiology
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• v.36 no.3
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• pp.192-195
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• 2000

Degenerate primevs corresponding to the consensus sequences of the copper-binding regions in the N- and Cterminal domains of fungal laccases were used to isolate laccase gene-specific sequences froin a white rot rungus Ganodern~a lucidrm w-hich has been known to strengthen the imnnne system. A 1.6 Kbp fragment was amplified by PCR and its base sequence was detenuiued. Locating seven iutrous within the base sequence, we could deduce its amino acid sequence. The nucleotide sequence witl~out introlls was 47Y0 identical to that of lee1 gene of Pametes wllosa; lhe identity in amino acid sequences of the two was 7994 The deduced amino acid seqoence was also sunilar to those of Coriolus versicolo~ kc3 (79%); Co~,iolz~s hirsutus phenolouiduse (78%), Trainetes vel.srcoloi. lccl (77%), Trametes ~!i/Iosa Ice2 (77%) and Trametes vemicolor kc4 (66%).