Organic Solvents Enhanced Spectrofluorimetric Method for Determination of Laccase Activity

A novel fluorimetric method for determination of laccase activity in organic solvents is proposed, based on the oxidation ofo-phenylenediamine (1,2-diaminobenzene, OPDA) catalyzed by laccase yielding 2,3-diaminophenazine. The optimal conditions for laccase in organic media areT=55°C, pH=6.5, 1.0×10?2mol/L OPDA, 1.25 mL ethanol, 1.25 mL 1,4-dioxane and 1.25 mL acetone. The linear range of the method proposed in ethanol, 1,4-dioxane and acetone media were 0.44–19.33, 0.11–20.85, 0.38–21.05 U with the detection limit of 0.088, 0.022, 0.076 U, respectively. The proposed method has been applied to the analysis of laccase activity of real samples with more accurate and sensitive than that of the previous method reported.

Optimization of Culture Components for Laccase Activity from Pleurotus Ostreatus P40 Using Response Surface Methodology

High enzymatic activity is required for laccase applications.Central composite design （CCD）-based response surface methodology （RSM） can effectively increase the enzymatic activity of Pleurotus ostreatus P40 in liquid substrate fermentation.Initial screening of the nutritional components was performed using a Plackett-Burman design.The variables,namely,bran,bagasse,Tween 80,and yeast extract,were found to have statistically significant effects on laccase activity.These variables were further optimized using CCD-based RSM.Optimal concentrations for the maximum laccase activity were 8.144 2 g/L bran,50 g/L bagasse,0.424 1 mL/L Tween 80,and 2.832 5 g/L yeast extract.Under optimized conditions,the maximum measured laccase activity reached 96 480 U/L,which was close to the predicted value （104 830 U/L） by RSM.Therefore,RSM can be used to optimize culture components for laccase activity from Pieurotus ostreatus P40.

Immobilization of Agaricus Bisporus Laccase on Ceramic-Chitosan Composite Support and Their Properties:Potential for Oily Wastewater Treatment

Laccase was immobilized on the ceramic-chitosan composite support by using glutaraldehyde as the cross-linking reagent. The immobilization conditions and characterization of the immobilized enzyme were investigated. The immobilization of laccase was successfully realized when 3.0 mL of 1.25 mg/mL of laccase at a pH value of 4.0 reacted with 0.15 g of ceramic-chitosan composite support(CCCS) at 4 ℃ for 24 h. The immobilized enzyme exhibited a maximum activity at pH 3.0. The optimal temperatures for immobilized enzyme were 25 ℃ and 50 ℃. The K_m value of immobilized laccase for ABTS was 66.64 μmol/L at a pH value of 3.0 at 25 ℃. Compared with free laccase, the thermal, operating and storage stability of immobilized laccase was improved after the immobilization.

A review of microbial laccase production and activity toward different biotechnological applications

Laccases are versatile enzymes that belong to the multi-copper oxidase family.This enzyme has several biotechnological applications because of its ablilty to oxidize a wide range of phenolic and non-phenolic substrates.However,their large-scale applicability in bioremediation and water treatment is hindered by high salt content and extreme pH values of the polluted media which also affects the stability,recovery and recycling of laccase.Apart from some bacteria,laccase is abundantly present in several lignin-degrading white-rot fungi viz.Ascomycetes,Deuteromycetes,and Basidiomycetes.Recently,lac-case has been employed in the development of biosensors as a medical diagnostic tool,biofuel cells,and in bioremediation purpose to remove herbicides,pesticides,and some toxic chemicals from the soil.However,most of the enzymes including laccase are normally unstable and susceptible to lose their activity over time.This might be avoided by maintaining the activity and lengthening the enzyme's lifespan through the use of appropriate immobilization procedures.The potential of laccase immobilized biocathodes for dye decolorization in microbial fuel cells has recently been studied.Immobilized laccase nanoparticles have potential uses as biocatalyst in the bioremediation of pollutants.In addition,advanced research considering microbial laccase has been conducted for its heterologous expression along with in silico protein engineering to attain maximum enzyme activity which can be potentially applied in different biotechnological sectors.Patent related to laccase also implied that this enzyme can be used as suitable catalyst for the production of promising anti-cancer drugs and even as a significant ingredient in cosmetics.

Enhanced oxidation of benzo[a]pyrene by crude enzyme extracts produced during interspecific fungal interaction of Trametes versicolor and Phanerochaete chrysosporium

The effects of interspecific fungal interactions between Trametes versicolor and Phanerochaete chrysosporium on laccase activity and enzymatic oxidation of polycyclic aromatic hydrocarbons （PAHs） were investigated. A deadlock between the two mycelia rather than replacement of one fungus by another was observed on an agar medium. The laccase activity in crude enzyme extracts from interaction zones reached a maximum after a 5-day incubation, which was significantly higher than that from regions of T. versicolor or P. chrysosporium alone. The enhanced induction of laccase activity lasted longer in half nutrition than in normal nutrition. A higher potential to oxidize benzo[a]pyrene by a crude enzyme preparation extracted from the interaction zones was demonstrated. After a 48 hr incubation period, the oxidation of benzo[a]pyrene by crude enzyme extracts from interaction zones reached 26.2%, while only 9.5% of benzo[a]pyrene was oxidized by crude extracts from T. versicolor. The oxidation was promoted by the co-oxidant 2,2＇-azinobis-3- ethylbenzthiazoline-6-sulphonate diammonium salt （ABTS）. These findings indicate that the application of co-culturing of white-rot fungi in bioremediation is a potential ameliorating technique for the restoration of PAH-contaminated soil.