Fungal laccases: versatile green catalyst for bioremediation of organopollutants

The need for the development of efficient and green oxidation technologies has increased the attention of researchers toward the use of enzymes as a substitute for conventional nonbiological methods. Among the different existing oxidases, laccases have been the choice for studying as a more ecofriendly option in comparison to the existing chemical processes. Fungal laccases are extracellular multicopper oxidases that use molecular oxygen to oxidize a wide variety of organic compounds ranging from phenolic, nonphenolic lignin-related compounds to highly recalcitrant environmental pollutants, by a radical-catalyzed reaction mechanism. Laccases can degrade lignin as well as decolorize and detoxify the industrial textile effluents, thus helping in the bioremediation of wastewater. Besides this, the substrate range of laccase can be extended by the addition of a mediator system. Over the last two decades, laccases from white-rot Basidiomycetes have been investigated extensively for their enormous potential applications in bioremediation in pulp and paper, textile, dye, and food industries. Many researchers have introduced laccase as a green catalyst for potential applications in various biotechnological processes including bioremediation of soils, water, and the development of environment-friendly processes, proving it to be a multifaceted enzyme. This chapter focuses on the potential applications of laccase enzymes with special reference to bioremediation. It also covers the natural roles of the laccases, structure, its physicochemical properties, substrates, reaction mechanism, inhibitors, categories, applications, economic feasibility, limitations, and future prospects of fungal laccases.