Molecular cloning for the production of genetically modified organisms for bioremediation

Environmental ecology is notably affected by anthropological activities. A major environmental concern regards soil and water pollution. Numerous physical and chemical methods are employed for the removal of pollutants, but bioremediation is superior among them. Wild strains (of bacteria or fungi) do not have a notable ability to degrade vast arrays of pollutants. Moreover, the environmental conditions at polluted sites also influence their growth. Therefore, genetically engineered bacteria are employed to achieve desired levels of bioremediation. The molecular cloning technique is the pioneer in constructing genetically engineered bacteria for specific purposes. It is the technique of selectively transferring a gene of interest (also called an insert) through expression vectors into the desired host to create a genetically engineered organism. The insert screening and selection are carried out through various methods, including DNA-based methods, RNA-based methods, the genetic fingerprinting method, PCR-based direct amplification, and the Next Generation Sequencing method. The use of genetically engineered bacteria is restricted due to ethical issues, for instance, the spreading of undesirable or unnatural genes to environments that might disturb ecological balance at the application site. Therefore, research is now focused on inserting certain traits like a "suicide system" and "killer gene" into expression vectors or in construction so that the genetically engineered bacteria will eliminate themselves from the environment once their role is over. In general, the present chapter deals with the basics of the molecular cloning technique, source and screening of insert gene(s), transformation of a recombinant DNA molecule in host bacterial cell, and selection of genetically engineered bacteria, as well as recent advances and ethical issues of genetic engineering techniques for bioremediation processes.