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.

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.