Extremozymes: A potential solution for heavy metal and organic pollutants detoxification

Extremozymes, a group of biocatalysts produced by extremophiles, have recently received great attention in biotechnology and various industrial applications. Typically, extremozymes are stable and function effectively under extreme conditions that would inactivate most of the mesophilic enzymes. The adaptation and properties of extremozymes to various harsh environments is based on the category of the source extremophiles including thermophiles, halophiles, alkaliphiles, acidophiles, psychrophiles, and radiphiles. Several extremozymes and extremophiles found significant role in bioremediation of various toxic pollutants including heavy metals and organic contaminants particularly at extreme conditions such as high salinity, acidity/alkalinity, temperature, etc. The studies show that several extremozymes such as chromate reductase, mercury reductase, and molybdate reductase can detoxify various heavy metals with high efficiency under extreme conditions. In addition, extremozymes such as alkane hydroxylase exhibited high biodegradation activity of crude oil pollutants. Several extremozymes, such as laccases peroxidases and hydrolases, have been investigated and applied for bioremediation of dye-contaminated industrial wastewater. Scientific efforts have been carried out on the utilization of extremozymes and extremophiles to develop efficient bioremediation technologies for industrial wastewater and polluted sites treatment. This review aims to give an overview on recent findings of bioremediation of various heavy metals and organic pollutants using various extremozymes, in addition to extremophiles ecology, adaptation mechanisms, properties extremozymes. Furthermore, it highlights the recent approaches for discovery of novel extremozymes, future, and challenges.