Enzymatic bioremediation: a smart tool to fight environmental pollutants

Enzyme-mediated bioremediation refers to the use of naturally occurring enzymes in microorganisms or plants to degrade or reduce harmful, undesirable, and recalcitrant environmental pollutants in order to clean contaminated sites. Enzymes are biocatalysts which lower the activation energy and facilitate quick and complete breakdown of substrates. The smaller size of enzymes as compared to microbial cells enables them to contact contaminants easily, facilitating rapid and effective degradation or reduction to an admissible or less harmful state. Advancements in nanotechnology coupled with enzyme technology have introduced a new concept of single-enzyme nanoparticles to treat pollutants or contaminants. These are more productive, selective, and faster than enzymatic treatment alone. Use of enzymes as compared to plants and microorganisms for bioremediation is rapid, cost-effective, accessible, and highly specific. The microbial whole cell needs the introduction of nutrients and air to maintain the optimum growth rate, and solvents and/or surfactants to enhance its bioavailability and immobilization. It is more feasible from an enzymatic perspective than using whole cells. Additionally, enzyme-mediated biotransformation reduces the generation of toxic by-products significantly as compared to chemical and some microbial remediations. Enzyme-based biosensors have further contributed to the miniaturization of analytical instruments with superior qualitative and quantitative estimation of compounds of interest present at the site. Enzyme technology has enhanced sensitivity and performance, providing a complete solution to all problems associated with microbial remediation. Despite such advantages, enzymatic remediation has also certain limitations which restrict its application to remediation processes, such as the production cost of enzymes, and their stability and activity across a wide range of contaminants. Being a sustainable and environment-friendly method, it has acquired the prime position in comparison to other remediation techniques available today to treat all types of waste materials mixed with soil, water, or air, rendering the degradation process highly controllable, specific, and easy to monitor and manage. This chapter discusses in detail bioremediation, its types, recent developments in enzyme-mediated smart bioremediation technologies, limitations and challenges to enzymatic bioremediation, and the way forward.