Microbial Enzymes In The Recycling Of Wastes

Abstract

The increasing volume of different types of wastes from various sources is an important environmental problem due to the ever growing migration and successive urbanization. Enzymes are biological catalysts from plant, animals or microorganisms with numerous potential applications. Microbial enzymes have been exploited in the recycling and management of wastes through enzymatic degradation and remediation resulting into less toxic useful products. Microbial enzymes are classified based on their mechanism of action as oxidoreductases, transferases, hydrolases, lyases, isomerases and ligases with oxidoreductases and hydrolases being the most utilized in waste treatment and recycling. Microbial oxidoreductases are involved in catalyzing oxidation-reduction reaction in harmful biodegradable materials to non-toxic products. The oxidoreductases employed in waste degradation include the oxygenases (mono and di-oxygenases), laccases and peroxidases. Microbial hydrolases catalyze the breakdown of waste biomass especially from food, agricultutral, chemical and biomedical industries by addition of water molecules to the waste materials. Some microbial enzymes with hydrolytic properties includes cellulase and hemicellulase, protease, lipase, amylase, lactase, xylanase and pullulanase. Compared to conventional chemical methods, recycling of wastes using microbial enzymes have great significance in bioremediation as they are specific, fast, relatively cheap, applied across a wide variety of contaminants, greatly reduce the waste and at the same time produce useful products. However, microbial enzymes are not devoid of limitations such as selection of the most suitable microbial enzyme for recycling and the ability of these enzymes to retain their active nature under normal conditions of operation for a prolonged period of time. Exploitation of molecular studies will in the near future provide a clearer picture on mechanisms of enzyme action either singly or in consortium with other enzymes during biodegradation and recycling of wastes to more valuable products.