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Enhanced production of laccase by

Wei SUN, Meiying XU, Chunyu XIA, Anhua LI, Guoping SUN

《环境科学与工程前沿（英文）》 2013年第7卷第2期页码 200-210 doi: 10.1007/s11783-012-0457-0

摘要： The effect of physical parameters of cultivation (load volume, temperature, pH, agitation, inoculum size, and incubation period) in the production of laccase by wood-rotting basidiomycete were studied using diluted molasses distillery wastewater (MDW) as a major composition. Using fractional factorial design, our study first identified load volume, agitation, and inoculum size as statistically significant factors. Optimal preferences and mutual interactions of the factors were then determined by the response surface method, which is based on the center composite design. A quadratic model was used to fit the experimental data. The optimized operational parameters for laccase production were determined to be the following: culture temperature of 25°C, pH 4, load volume of 40 mL diluted MDW in 150 mL flask, agitation rate of 183 r·min , inoculation of 11.5% v/v, and cultivation time of 6 d. The experimental validation under these conditions (the maximum laccase production of 2198.2 U·mL was within the confidence interval) subsequently verified the accuracy of the constructed model. Moreover, the removal of chemical oxygen demand and nitrogen of MDW reached 62.85% and 48.00% respectively, and the decolorization ratio under the optimal condition was 41.85%. The enhanced production of laccase by is a new recovery strategy for MDW.

关键词： laccase Coriolus hirsutus fractional factorial design response surface method molasses distillery wastewater

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Immobilization of laccase on organic–inorganic nanocomposites and its application in the removal of phenolic

《化学科学与工程前沿（英文）》 2023年第17卷第7期页码 867-879 doi: 10.1007/s11705-022-2277-5

摘要： Polydopamine-functionalized nanosilica was synthesized using an inexpensive and easily obtainable raw material, mild reaction conditions, and simple operation. Subsequently, a flexible spacer arm was introduced by using dialdehyde starch as a cross-linking agent to bind with laccase. A high loading amount (77.8 mg∙g^‒1) and activity retention (75.5%) could be achieved under the optimum immobilization conditions. Thermodynamic parameters showed that the immobilized laccase had a lower thermal deactivation rate constant and longer half-life. The enhancement of thermodynamic parameters indicated that the immobilized laccase had better thermal stability than free laccase. The residual activity of immobilized laccase remained at about 50.0% after 30 days, which was 4.0 times that of free laccase. Immobilized laccase demonstrated excellent removal of phenolic pollutants (2,4-dichlorophenol, bisphenol A, phenol, and 4-chlorophenol) and perfect reusability with 70% removal efficiency retention for 2,4-dichlorophenol after seven cycles. These results suggested that immobilized laccase possessed great reusability, improved thermal stability, and excellent storage stability. Organic–inorganic nanomaterials have a good application prospect for laccase immobilization, and the immobilized laccase of this work may provide a practical application for the removal of phenolic pollutants.

关键词： polydopamine pollutant removal thermodynamic phenolic pollutants immobilized laccase

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Removal of 17β-estradiol in laccase catalyzed treatment processes

XIA Qing,KONG Deyang,LIU Guoqiang,HUANG Qingguo,ALALEWI Aamr,LU Junhe

《环境科学与工程前沿（英文）》 2014年第8卷第3期页码 372-378 doi: 10.1007/s11783-013-0567-3

摘要： The removal of 17β-estradiol (E2) in laccase catalyzed oxidative coupling processes was systematically studied in this work. We focused on the influence of pH and natural organic matter (NOM) on the performance of the enzymatic treatment processes. It was found that the optimal pH for E2 removal was between 4 and 6. The removal of E2 was slightly inhibited in the presence of NOM. Enzymatic transformation of E2 was second-order in kinetics with first-order to both the concentrations of the enzyme and contaminant. Mass spectrum (MS) analysis suggested that coupling products were formed through radical-radical coupling mechanism. The results of this study demonstrated that laccase catalyzed oxidative coupling process could potentially serve as a treatment strategy to control steroid estrogens.

关键词： 17β-estradiol laccase oxidative coupling processes kinetics mechanisms

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Transformation of triclosan by a novel cold-adapted laccase from

Yuanyuan Shi, Deyang Kong, Jiayang Liu, Junhe Lu, Xiaoming Yin, Quansuo Zhou

《环境科学与工程前沿（英文）》 2017年第11卷第3期 doi: 10.1007/s11783-017-0927-5

摘要： This work investigated the transformation of triclosan (TCS) by laccase produced by a pathogen isolated from rotten tomato. The pathogen was characterized as sp. FQ, belonging to subphylum . The laccase exhibited cold-adaptation with relatively high activity at 20°C. The laccase could effectively transform TCS. Approximately 62% TCS could be removed at dose of 1.0 unit·mL in 120 min. The reaction rate appeared to be to the concentration of the substrate, suggesting the laccase activity remained stable during the reaction. Transformation products of TCS were analyzed by mass spectrometry and it was revealed that TCS dimers were formed via radical coupling pathways. During this process, laccase catalyzed oxidation of TCS to form a radical intermediate is the rate limiting step. However, this step can be reversed by humic acid. Overall, the laccase showed great potential in the treatment of phenolic contaminants. Since laccase is widely presented in natural environment, this study also revealed an important pathway involved in the transformation of phenolic contaminants in the environment.

关键词： Laccase Botrytis cinerea Triclosan Transformation Kinetics

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Biomineralization-inspired copper-cystine nanoleaves capable of laccase-like catalysis for the colorimetric

Miao Guan, Mengfan Wang, Wei Qi, Rongxin Su, Zhimin He

《化学科学与工程前沿（英文）》 2021年第15卷第2期页码 310-318 doi: 10.1007/s11705-020-1940-y

摘要： Recently, many efforts have been dedicated to creating enzyme-mimicking catalysts to replace natural enzymes in practical fields. Inspired by the pathological biomineralization behaviour of L-cystine, in this study, we constructed a laccase-like catalyst through the co-assembly of L-cystine with Cu ions. Structural analysis revealed that the formed catalytic Cu-cystine nanoleaves (Cu-Cys NLs) possess a Cu(I)-Cu(II) electron transfer system similar to that in natural laccase. Reaction kinetic studies demonstrated that the catalyst follows the typical Michaelis-Menten model. Compared with natural laccase, the Cu-Cys NLs exhibit superior stability during long-term incubation under extreme pH, high-temperature or high-salt conditions. Remarkably, the Cu-Cys NLs could be easily recovered and still maintained 76% of their activity after 8 cycles. Finally, this laccase mimic was employed to develop a colorimetric method for epinephrine detection, which achieved a wider linear range (9–455 μmol·L ) and lower limit of detection (2.7 μmol·L ). The Cu-Cys NLs also displayed excellent specificity and sensitivity towards epinephrine in a test based on urine samples.

关键词： biomineralization laccase L-cystine colorimetric detection enzyme mimic

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Extraction and biodegradation of ginkgolic acids from

Qi LI, Wei SUN, Yan JIANG, Fuliang CAO, Guibin WANG, Linguo ZHAO

《农业科学与工程前沿（英文）》 2017年第4卷第4期页码 465-472 doi: 10.15302/J-FASE-2017181

摘要： Ginkgolic acids are unwanted constituents in standard leaves extracts. Thus, for the quality control of ginkgo extracts, it is important to establish an effective degradation method, with high catalytic efficiency and safety, to remove ginkgolic acids. Laccases are oxidases with potential for application in elimination of hazardous phenolic compounds. In this study, single-factor and orthogonal experiments were used to optimize extraction of ginkgolic acid from sarcotestae. The results showed that ethanol was the best solvent, with the highest extraction rate for ginkgolic acid at 85% ethanol. On this basis, we measured ethanol volume fraction, extraction time, temperature and solid-liquid ratio using an orthogonal experiment. By using absorbance of 310 nm as standard, the optimal extraction conditions were 85% ethanol with, solid-liquid ratio of 1:14 at 40°C for 12 h. These conditions gave a ginkgolic acid yield of 73.1 mg·g . Subsequently, recombinant laccase was used to degrade the ginkgolic acid in several laccase/mediator systems, of which LacC was the best. At 50°C, pH 4.5, enzyme concentration of 0.01 U·mL , 0.5 mmol·L mediator ABTS and reaction time of 3 h, the degradation rate of ginkgolic acid reached 100%. These results lay the foundation for research on and application of biological enzymes for detoxification of extracts.

关键词： biodegradation extraction ginkgolic acid laccase orthogonal method