Biochemical characterization of free and immobilized laccase application in pollution abatement

Abstract

Water pollution by the discharge of dye-containing effluents, is a serious ecological problem all over the world. Public demands for colour-free discharges into water have given decolorization of a variety of industrial wastewater the top priority. The oxidative enzymes approach is believed to be a promising technology, since it is cost-effective, environment friendly, highly specific and does not produce sludge. An industrial application of laccase for dye decolorization requires large amounts of readily available laccase at low cost, which is stable under operational conditions, and recyclable. Therefore, the first goal of this study was the search for an efficient production and purification system of the laccase enzyme. Sixteen fungal species were obtained from various culture collection centers in India, and screened for laccase activity by the indicator plate method; of these five species were found to be laccase-positive. Growing laccase utilization in numerous biotechnological applications encourages the search for high benefit/cost ratio purification methodology such as Three Phase Partitioning (TPP). The next goal of the present study was to develop an immobilization protocol for laccase enzyme, and its further use in dye removal. Cross-Linked Enzyme Aggregates (CLEAs) is a simple and effective methodology for laccase immobilization. The biodegradation of dyes and effluents was monitored by UV vis spectroscopy and HPLC. The results showed that color was removed by UV-visible spectroscopy. The HPLC analysis confirmed the biotransformation of dyes and effluents into several degradation products. Toxicological studies of the growth of agriculturally important plants like Phaseolus mungo and Triticum aestivum conclusively determinates the toxicity of dyes and comparatively less toxic nature of metabolites formed after dye degradation by CLEAs laccase. newline newline newline