• Journal of the Korean Wood Science and Technology
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• 제14권3호
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• pp.36-42
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• 1986

The production media and the enzymatic charateristics of laccase from Flammulina velutipes were investigated. The activity of laccase during incubation reached to the maximum at the 40 days of incubation in the case of Barley straw medium. The maximum laccase activity in Barley straw medium was 5 and 16 times higher than those in Onion basic and Sawdust media, respectively. The laccase from Flammulina velutipes has the optimum pH of 6.6 and showed to be stable at relatively broad pH range. 4.5-9.5. Temperature stability showed that above 96% activity could be preserved after holding at 40$^{\circ}C$ for 40 minutes. At the above 70$^{\circ}C$, the laccase activity decreased very rapidly. The Km value of the laccase was estimated to be 28.0 mM which is much higher than that of the laccase from Pleurotus ostreatus. Organic solvents for precipitiation of the enzyme did not inactivation the laccase. Sodium azide which was added for preventing microbial deterioration affected significantly the inactivation of laccase, but this activity was recovered completely by precipitating the enzyme with acetone.

• Journal of the Korean Wood Science and Technology
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• 제29권3호
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• pp.104-111
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• 2001

There are some evidence that active enzymatic proteins, e.g. fungal laccase, exist in the naturally occured soil humus. This study was performed to investigate the covalent binding of fungal laccase to the humic acid-iron complex, and to measure laccase activity of immobilized ones. Seven methods were adopted to form the covalent binding of fungal laccase with soil humic acids complexed with iron. Using these seven methods it was possible to change the dimension of spacer arm between laccase and support, and also to regulate the mode of covalent binding of this enzyme. The spacer arm was regulated from 2C to 11C. There was not observed any straight relationship between the spacer arm longitude and the laccase activity after immobilization, but the binding mode more effective than the former. Three out of the seven methods gave the high activity of immobilized laccase, and which active products of laccase immobilization was stable up to 10 days after the process. It is indicated that natural soil condition might be prevented the laccase activation by the toxic influence of some phenolic humic compounds. It was shown, for the first time, the possibilities to obtain the high activity of fungal laccase by binding to humic acids, and especially in complex with iron.

• Journal of Microbiology and Biotechnology
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• 제23권4호
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• pp.565-571
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• 2013

This is the first report on using Catathelasma ventricosum for production of fruiting body and lignocellulosic enzymes. To improve the laccase activity and productivity of mushroom, the substrate was added with different supplements (eight aromatic compounds, $Mn^{2+}$, and $Cu^{2+}$). Based on the results, all these supplements can improve the laccase activity and productivity of C. ventricosum, and it seems that there is a critical value of laccase activity that affects the productivity of C. ventricosum. In addition, when Penicillium decumbens was inoculated into the substrate that had been cultivated with C. ventricosum for 20 days, the highest values of laccase activity, FPA activity, and productivity of C. ventricosum were obtained. Moreover, the laccase activity showed a positive correlation with the productivity of C. ventricosum. Finally, the effect of $Mn^{2+}$, $Cu^{2+}$, and P. decumbens on laccase activity was investigated by response surface methodology (RSM).

• Journal of Microbiology and Biotechnology
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• 제11권3호
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• pp.369-375
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• 2001

Urushiol, a natural monomeric oil, was used to prepare a detergentless micro-emulsion with water and 2-propanol The formation of micro-emulsion was verified by conductivity measurements and dynamic light scattering. The conductivity data showed phase change dynamics, a characteristics of micro-emulsions, and subsequent dynamic light scattering study further confirmed the phenomenon. Average water droplet diameter was 10 nm to 500 nm when the molar ratio of 2-propanol ranged from 0.40 to 0.44 . Earlier studies were performed on toluene and hexane, in which the insoluble substrate in water phase was added to the solvents to be reacted on by enzymes. However, in the present urushiol system, urushiol was used as both solvent and substrate in the laccase polymerization of urushiol. The laccase activity in the system was examined using polymerization of urushiol. The laccase activity in the system was examined using syringaldezine as a substrate, and the activity increased rapidly near the molar ratio of 2-propanol at 0.4, where micro-emulsion started. The activity rose until 0.46 and fell dramatically thereafter. The study of laccase activity in differing mole fractions of 2-propanol showed the existence of an ‘optimal zone’, where the activity of laccase was significantly higher. In order to analyze urushiol polymerization by laccase, a bubble column reactor using a detergentless micro-emulsion system was constructed. Comparative study using other organic solvents systems were conducted and the 2-propanol system was shown to yield the highest polymerization level. The study of laccase activity at a differing mole fraction of 2-propanol showed the existence of an ‘optimal zone’ where the activity was significantly higher. Also, 3,000 cP viscosity was achieved in actual urushi processing, using only 1/100 level of laccase present in urushi.

• 생명과학회지
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• 제25권6호
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• pp.673-679
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• 2015

본 연구에서는 재비늘버섯(Pholiota highlandensis)의 리그닌 분해 활성을 확인하고, laccase 생산을 위한 최적 배양 조건을 조사하였다. 재비늘버섯 균사체로부터 laccase를 생산하기 위한 배지조건을 조사한 결과, 다양한 합성 배지 중에서 Coriolus versicolor 배지(2% dextrose, 0.4% peptone, 0.6% yeast extract, 0.046% KH₂PO₄, 0.1% K₂HPO₄, 0.05% MgSO₄·7H₂O)가 가장 높은 laccase 활성을 나타내었다. Laccase생산에 대한 배양 조건을 최적화하기 위하여 Coriolus versicolor 배지의 조성 중에서 탄소원, 질소원, 인산원, 무기염에 대한 영향을 조사하였다. 탄소원, 질소원, 인산원, 무기염은 각각 2% fructose, 0.4% peptone 및 0.6% yeast extract, 0.05% NaH₂PO₄, 0.05% MgSO₄·7H₂O의 경우에 가장 높은 효소활성을 나타내었다. 본 균주는 몇 가지 방향족 화합물에 의해 laccase 생산이 유도되었고, guaiacol을 첨가할 경우 25℃에서 11일 동안 배양하였을 때 효소의 활성이 최대치(114.1 U/ml)에 도달하였다. 또한 본 균주의 laccase 생산을 위한 최적 pH와 온도는 각각 8.0과 35℃를 나타내었다. 최적 조건에서 배양된 균사체 배양 상등액을 Native-PAGE로 전기영동한 후 ABTS를 기질로 사용하여 활성염색을 수행한 결과, 약 90 kDa 부근에서 laccase 활성을 가지는 1개의 밴드를 확인하였다.

• 산업기술연구
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• 제37권1호
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• pp.16-20
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• 2017

A new putative laccase gene (soncotA) which show 78% homology with that from Bacillus licheniformis (liccotA) was isolated from draft genome sequence of Bacillus sonorensis KCTC 13918. A 1,545 bp of PCR product corresponding 514 amino acids was cloned into NdeI-NotI site of pET21c and expressed as soluble form in E. coli. About 59 kDa size of recombinant laccase was purified into homogenity by Ni-NTA column and laccase activity was confirmed by zymography. The enzymatic properties of recombinant laccase were characterized. The specific activity of B. sonorensis laccase was 0.033 fold lower than that of Bacillus licheniformis laccase. The finding of new laccase gene broadened the enzymatic diversity of Bacillus species laccases.

• Journal of the Korean Wood Science and Technology
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• 제47권2호
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• pp.210-220
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• 2019

This work aimed to evaluate the influence of culture conditions on laccase production in the co-culture of wood-rotting fungus with Trichoderma sp. The effects of infection extent, infection time, and culture filtrate of Trichoderma sp. on the laccase production by wood-rotting fungus in co-culture were examined. T. rubrum LKY-7 and T. longibrachiatum were selected as fungi which are effective in co-culture for laccase production. A significant increase in laccase activity was observed when T. rubrum LKY-7 was co-cultured with T. longibrachiatum in glucose-peptone liquid medium, yielding an increase of more than 5 times in laccase activity, as compared with control. Laccase production by T. rubrum LKY-7 during co-culturing was significantly influenced by the infection extent and the infection time of T. longibrachiatum. Maximal laccase activity was obtained when T. rubrum LKY-7 culture was infected by T. longibrachiatum after 3 days of cultivation at an inoculum size ratio of 0.5 to 1. The addition of culture filtrate or autoclaved mycelium of T. longibrachiatum to T. rubrum LKY-7 culture did not significantly enhance laccase production by T. rubrum LKY-7 as compared with control (mono cultures of T. rubrum LKY-7).

• 한국미생물·생명공학회지
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• 제13권1호
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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 Microbiology and Biotechnology
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• 제33권1호
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• pp.127-134
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• 2023

Laccase activity is influenced by copper (Cu) as an inducer. In this study, laccase was immobilized on Cu and Cu-magnetic (Cu/Fe₂O₄) nanoparticles (NPs) to improve enzyme stability and potential applications. The Cu/Fe₂O₄ NPs functionally activated by 3-aminopropyltriethoxysilane and glutaraldehyde exhibited an immobilization yield and relative activity (RA) of 93.1 and 140%, respectively. Under optimized conditions, Cu/Fe₂O₄ NPs showed high loading of laccase up to 285 mg/g of support and maximum RA of 140% at a pH 5.0 after 24 h of incubation (4℃). Immobilized laccase, as Cu/Fe₂O₄-laccase, had a higher optimum pH (4.0) and temperature (45℃) than those of a free enzyme. The pH and temperature profiles were significantly improved through immobilization. Cu/Fe₂O₄-laccase exhibited 25-fold higher thermal stability at 65℃ and retained residual activity of 91.8% after 10 cycles of reuse. The degradation of bisphenols was 3.9-fold higher with Cu/Fe₂O₄-laccase than that with the free enzyme. To the best of our knowledge, Rhus vernicifera laccase immobilization on Cu or Cu/Fe₂O₄ NPs has not yet been reported. This investigation revealed that laccase immobilization on Cu/Fe₂O₄ NPs is desirable for efficient enzyme loading and high relative activity, with remarkable bisphenol A degradation potential.

• 펄프종이기술
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• 제38권5호
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• pp.1-8
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• 2006

This study was performed to evaluate extensive electrochemical characteristics of 23 commercially available mediators for laccase. Electrochemical properties, interactions with laccases, and ability to degrade lignin were compared for selected mediators. Among them, NNDS has very similar electrochemical properties in terms of reversibility and redox potential (about 470 mV vs. Ag/AgCl at pH=7) compared to ABTS which is a well-known mediator. Specific activity of purified laccase from Cerrena unicolor was determined by both 2,2'-azino-bis-(3-ethylbenz-thiazoline-6-sulfonic acid) (ABTS) and 1-nitroso-2-naphthol -3,6-disulfonic acid (NNDS). The specific activity of the laccase was 23.2 units/mg with ABTS and 21.2 units/mg with NNDS. The electron exchange rate for NNDS with laccase was very similar to that for ABTS, which meant that NNDS had similar mediating capability to ABTS. Determining methanol concentration after reacting with laccase compared to lignin degradation capabilities of both ARTS and NNDS. ARTS or NNDS alone cannot degrade lignin, but in the presence of laccase enhanced the rate of lignin degradation. ABTS showed better activity in the beginning, and the reaction rate of NNDS with lignin was about a half of that of ABTS at 10 minute, but the final concentration of methanol produced in 1 hour was very similar each other. The reason for similar methanol concentration for both ABTS and NNDS can be interpreted as the initial activity of ABTS was better than that of NNDS, but ABTS would be inhibited laccase activity more during the incubation.