• Journal of Microbiology
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• v.43 no.6
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• pp.555-560
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• 2005

Laccase is one of the ligninolytic enzymes of white rot fungus Trametes versicolor 951022, a strain first isolated in Korea. This laccase was purified 209-fold from culture fluid with a yield of $6.2\%$ using ethanol precipitation, DEAE-Sepharose, Phenyl-Sepharose, and Sephadex G-100 chromatography. T. versicolor 951022 excretes a single monomeric laccase showing a high specific activity of 91,443 U/mg for 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) as a substrate. The enzyme has a molecular mass of approximately 97 kDa as determined by SDS-PAGE, which is larger than those of other laccases reported. It exhibits high enzyme activity over broad pH and temperature ranges with optimum activity at pH 3.0 and a temperature of $50^{\circ}C$. The $K_m$ value of the enzyme for substrate ABTS is $12.8{\mu}M$ and its corresponding $V_{max}$ value is 8125.4 U/mg. The specific activity and substrate affinity of this laccase are higher than those of other white rot fungi, therefore, it may be potentially useful for industrial purposes.

• Korean Journal of Microbiology
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• v.39 no.3
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• pp.201-205
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• 2003

Laccase, lignin- and manganese peroxidase are implicated in the lignin degradation. The nucleotide sequences of four copper-binding domains in fungal laccases, and heme-binding domains of lignin- and manganese peroxidases are well conserved, and therefore these short fragments can be used for the PCR for the gene amplification. We synthesized several PCR primers according to their sequences, and run PCR to amplifiy the lignin degrading genes of Trametes versicolor isolated in Korea. PCR products were cloned with pGEM-T vector in order to determine their nucleotide sequences. A laccase fragment (1.3 kb) showed 65-97％ homologies, lignin peroxidase fragment (185 bp) showed 80-95％ homologies, and manganese peroxidase fragment (443 bp) showed 61-83％ homologies when compared with other white-rot fungal enzymes.

• The Korean Journal of Mycology
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• v.39 no.1
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• pp.48-52
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• 2011

Breeding of Lentinula edodes generates a number of hybrid strains that are subject to evaluation for good traits for the mushroom production. As an effort to understand biochemical properties of the hybrid strains, this study tried to develop a fast and easy method for comparison of the ability of producing extracellular laccase among hybrid strains of Lentinula edodes. For this aim, we estimated the effect of media types and chromagenic chemicals on the detection of extracellular laccase in seven hybrid strains of L. edodes. When Remazol Brilliant Blue R (RBBR) dye was used for chromagenic reaction, the detection of the enzyme activity was feasible both in the solid and liquid media containing not potato dextrose but malt extract as a nutrient component. When guaiacol was used for chromagenic reaction, the detection of the enzyme activity was feasible both in the solid and liquid media containing either potato dextrose or malt extract as a nutrient component. Malt extract-based liquid culture with RBBR or guaiacol in 2 ml microfuge tube allowed us to economically and quantitatively detect and compare the enzyme activity within 3 days among the tested hybrid strains of L. edodes.

• The Korean Journal of Mycology
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• v.15 no.2
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• pp.99-170
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• 1987

The production and properties of laccase(E.C.1.10.3.2) from Coriolus versicolor were studied. The results were as follows; The nutritional optimum conditions for laccase production were 1% indulin At, 0.3% peptone 0.1% $KH_2PO_4$, 0.02% $MgSO_4$, 0.1 mg% $CuSO_4$.and 0.005 mg% thiamine HCI. The optimum temperature and pH of laccase production were $25^{\circ}C$ and 5.0, and respectively, and the cultural period was 20 days. The optimum pH and temperature for the activity were 4.6 and $40^{\circ}C$, respectively. The enzyme was almost stable under the temperature of $40^{\circ}C$ and within the pH range of 4.0-5.0. The enzyme was stable at $40^{\circ}C$ for 30 min. $Cu^{++}$, $Fe^{++}$ and $Ca^{++}$ activated the enzyme activity, but $Mn^{++}$ and $Hg^{++}$ were inhibited. The enzyme was totally inhibited by 1 mM sodium azide and 1 mM potassium cyanide, and partly inhibited by EDTA and hydroxyamine.

• Applied Biological Chemistry
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• v.41 no.5
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• pp.384-389
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• 1998

The herbicide propanil and its metabolite, DCA were incubated with oxidative catalysts in the presence or absence of humic monomers to evaluate the incorporation of them into humic substances. Propanil and DCA underwent little or no transformation by oxidatve catalysts in the absence of humic monomers. In the presence of humic monomers, the most effective co-substrate for transformation of propanil was syringic acid by laccase and HRP, that of DCA was catechol by laccase and HRP, and protocatechuic acid by birnessite. The transformation of DCA was the highest when it was incubated with catechol at pH 8.0 during 24 hrs by laccase, and with catechol at pH 3.0 during 2 hrs by HRP, and with protocatechuic acid at pH 5.0 during 2 hrs by birnessite. The DCA transformation increased with increasing concentration of humic monomers. The transformation of DCA was increased with about 5 times when it was incubated with lactase and birnessite together than lactase alone, but that of it was not effected when it was incubated with HRP and birnessite together. When DCA was incubated with dissolved organic carbon in the presence of oxidative catalysts, the transformation of it was not increased by laccase and birnessite but increased by HRP.

• The Korean Journal of Mycology
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• v.38 no.2
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• pp.152-159
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• 2010

The influence of urushiol, as an allergen on laccase property of Fomitella fraxinea was investigated. The enzyme production was reached to the highest level after 10 days, cultivation and the activity and mycelial biomass were increased by 2.5 and 1.5 folds, respectively, by adding urushiol in the culture medium. In liquid cultures using a Cu Mn-free medium, laccase lactivity was decreased by 3.8-9.2 folds, with similar dry cell weight. Two isoenzymes, were purified using anion exchange, hydrophobic interaction and size-exclusion chromatographies. Both isoenzymes are monomeric proteins, with $M_W$ around 67 kDa(Lac1) and 66 kDa(Lac2), and isoelectric points of 3.67 and 3.81. The optimal conditions for purified isoenzymes were found to be pH 4.5-5.0 and $30-35^{\circ}C$. Activity decreased by the addition of $Fe^{2+}$, $Mg^{2+}$, $Na^+$, and strongly inhibited by EDTA and sodium azide.

• Journal of the Korean Wood Science and Technology
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• v.17 no.3
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• pp.52-60
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• 1989

This study was carried out to know the possibility of simultaneous utilization of laccase from white-rot fungus with cellulase on enzymatic hydrolysis of cellulosic substrate from autohydrolyzed oak wood. Laccases from 3 white-rot fungi, Pleurotus ostreatus. Ganoderma lucidum, and Phanerochaete chrysosporium, were isolated, purified and measured their activities. The highest activity was shown in Pleurotus ostreatus and the lowest in Phanerochaete chrysosporium. Laccase from Pleurotus ostreatus has optimum pH of 5.94, Km value of 3.209 mM and appeared to be stable at relatively wide pH range, 4.7-8.72. Temperature stability showed that 60% activity was preserved after 40 minutes at $50^{\circ}C$. Laccase from Ganoderma lucidum reached to the maximum activity during 15-20 day incubation. This enzyme has optimum pH of 6.45, Km value of 6.71 mM and pH range of 5.0-9.0 for stabilization. 95% activity was preserved at $30^{\circ}C$ and 58% activity at $50^{\circ}C$. Concerned to the enzymatic hydrolysis of cellulosic substrate with both enzymes, cellulase and laccase, simultaneously, mixed culture filtrates and mycellium extracts were shown higher hydrolysis rates than those of Trichoderma viride. There were no significant differences in the extent of hydrolysis among various mixed culture filtrates and mycellium extracts.

• Korean Journal of Microbiology
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• v.30 no.2
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• pp.78-82
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• 1992

The dikaryon of Trimorphonzycc,.~ papilioncicc.ous, one of basidiornycetous yeast needed thiamine as a growth factor and required relatively simple nutrient components. This organism grem best at 25$^{\circ}$C. anci showed broad pH range (pH 4.0-7.0). It was groM,n in liquid minimal media with various carbon sources and they could be classilied into 3 groups as follows. Glucose. fructose. mannose, sucrose and xylose (A gi.oup) supportecl good growth (>OD 0.8), and showed poor laccase activity (less than 1.5 u'mg protein). Galactose and gluconate (B group) showed moderate growth (01) 0.3-0.6). and hail moderatc crlzyrne activity (4-6u). Arabinosc. lactose. maltose ant1 pyruvate (C 5roup) showed poor growth (OD 0.1-0.2). and showed high enzyme activity (higher than 8 u). Kibosc, acetate. citrate. lactate and oxaloacetate showed no growth. When the yeast was grown in a medium which had two carbon sources (glucose and arabinose). laccase was regul;~tecl by the cutahoiitc repression.

• Journal of Mushroom
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• v.15 no.4
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• pp.168-177
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• 2017

To evaluate effects of ligninolytic enzyme type on the mycelial response and ligninolytic enzyme production during interspecific interactions among wood-rotting fungi, 4 fungal strains, Trichophyton rubrum LKY-7, Trichophyton rubrum LSK-27, Pycnoporus cinnabarinus, and Trichoderma viride, were selected. Regarding ligninolytic enzyme production, LKY-7 secreted laccase and manganese peroxidase (MnP), P. cinnabarinus secreted only laccase, and LSK-27 secreted only MnP in glucose-peptone medium, while T. viride did not produce any ligninolytic enzymes. In the co-culture of LKY-7 with P. cinnabarinus, the formation of aerial mycelium was observed and the enhancement of laccase activity owing to interspecific interaction appeared to be very low. In the co-culture of LKY-7 and P. cinnabarinus with LSK-27, a hypha-free clear zone was observed, which resulted in deadlock, and increased laccase or MnP activity was detected at the interaction zone. The interaction responses of LKY-7, P. cinnabarinus, and LSK-27 with T. viride were characterized by the formation of mycelial barrages along the interface. As mycelial barrages were observed at the T. viride territory and no brownish pigment was observed in the mycelial barrages, it is suggested that laccase and MnP are released as part of an offensive response, not as a defensive response. The co-culture of P. cinnabarinus with T. viride lead to the highest enhancement in laccase activity, yielding more than 14-fold increase in laccase activity with respect to the mono-culture of P. cinnabarinus. MnP activities secreted by LKY-7 or LSK-27 was generally low in interspecific interactions.

• Journal of Microbiology and Biotechnology
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• v.24 no.5
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• pp.639-647
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• 2014

Laccases have a broad range of industrial applications. In this study, we immobilized laccase on $SiO_2$ nanoparticles to overcome problems associated with stability and reusability of the free enzyme. Among different reagents used to functionally activate the nanoparticles, glutaraldehyde was found to be the most effective for immobilization. Optimization of the immobilization pH, temperature, enzyme loading, and incubation period led to a maximum immobilization yield of 75.8% and an immobilization efficiency of 92.9%. The optimum pH and temperature for immobilized laccase were 3.5 and $45^{\circ}C$, respectively, which differed from the values of pH 3.0 and $40^{\circ}C$ obtained for the free enzyme. Immobilized laccase retained high residual activities over a broad range of pH and temperature. The kinetic parameter $V_{max}$ was slightly reduced from 1,890 to 1,630 ${\mu}mol/min/mg$ protein, and $K_m$ was increased from 29.3 to 45.6. The thermal stability of immobilized laccase was significantly higher than that of the free enzyme, with a half-life 11- and 18-fold higher at temperatures of $50^{\circ}C$ and $60^{\circ}C$, respectively. In addition, residual activity was 82.6% after 10 cycles of use. Thus, laccase immobilized on $SiO_2$ nanoparticles functionally activated with glutaraldehyde has broad pH and temperature ranges, thermostability, and high reusability compared with the free enzyme. It constitutes a notably efficient system for biotechnological applications.