Genome Editing and Genetically Engineered Bacteria for Bioremediation of Heavy Metals

Genetic engineering involves the manipulation of DNA to either improve, enhance or repair a function by using recombinant DNA technology, which has contributed greatly to the fields of medicine and agriculture. In recent times, the CRISPR-Cas system of gene editing has come to the forefront of genome engineering, transforming disease treatment strategies and the production of modified crops. Industrial activities cause environmental pollution by releasing heavy metal-containing xenobiotic compounds into the environment and affect animal health by causing organ dysfunction and even cancer. Although plants utilize heavy metals from soil in small quantities for their growth, excessive exposure leads to disruption of plant cell machinery and reduces productivity. Similarly, heavy metals degrade soil health by interfering with microbial processes that contribute to soil fertility. Apart from existing methods available for the remediation of contaminated sites, bioremediation is emerging as a potent technique due to its high efficacy, cost-effectiveness and ecofriendly nature. Microbes possess a number of physiological and biochemical properties that have been exploited for the removal and detoxification of metal pollutants. This chapter elaborates on the approaches of gene editing and the development of genetically engineered bacteria to modify the expression of specific genes coding for enzymes that take part in the degradative or detoxification pathway of metals and xenobiotic compounds. It is crucial to address the scope as well as limitations involved in the use of genetically engineered microbes to ensure a safe and cost-effective method for the bioremediation of heavy metal contaminants.