Laccases: structure, function, and potential application in water bioremediation

Abstract

The global rise in urbanization and industrial activity has led to the production and incorporation of foreign con‑ taminant molecules into ecosystems, distorting them and impacting human and animal health. Physical, chemical, and biological strategies have been adopted to eliminate these contaminants from water bodies under anthropo‑ genic stress. Biotechnological processes involving microorganisms and enzymes have been used for this purpose; specifcally, laccases, which are broad spectrum biocatalysts, have been used to degrade several compounds, such as those that can be found in the efuents from industries and hospitals. Laccases have shown high potential in the biotransformation of diverse pollutants using crude enzyme extracts or free enzymes. However, their application in bioremediation and water treatment at a large scale is limited by the complex composition and high salt concentra‑ tion and pH values of contaminated media that afect protein stability, recovery and recycling. These issues are also associated with operational problems and the necessity of large-scale production of laccase. Hence, more knowledge on the molecular characteristics of water bodies is required to identify and develop new laccases that can be used under complex conditions and to develop novel strategies and processes to achieve their efcient application in treating contaminated water. Recently, stability, efciency, separation and reuse issues have been overcome by the immobilization of enzymes and development of novel biocatalytic materials. This review provides recent information on laccases from diferent sources, their structures and biochemical properties, mechanisms of action, and applica‑ tion in the bioremediation and biotransformation of contaminant molecules in water. Moreover, we discuss a series of improvements that have been attempted for better organic solvent tolerance, thermo-tolerance, and operational stability of laccases, as per process requirements.