Genetically Engineered Microorganisms for Bioremediation Processes: GEMs for Bioremediaton

1. Introduction

The introduction of synthetic compounds into the environment, composed with the massive removal of natural materials to distinctive environmental compartments. In some cases this accumulation can constitute a severe hazard. During the past several decades as a result of human activities, has resulted in the various elements of the chemical structures of many of these pollutants are beyond the biodegradation capabilities of microorganisms by existing pathways (Pieper & Reineke, 2000; Dejoinghe et al., 2000; Bruins et al., 2000). A vast number of pollutants and waste materials containing heavy metals are disposed into the environment per annum. The contaminants causing ecological problems leading to imbalance between nature and global concern. Thus, control and treatment strategies to reduce the hazardous effects of pollutants are needed. Instead, conventional physical, chemical and thermal processes have high costs; require high energy demand and consumption of many chemical reagents. The search for alternative methods for traditional methods resulted in evolution of bioremediation techniques. It approaches is cost effective, economical and alternative to conventional treatments, which generally incinerations, immobilization of the pollutants. Generally used approach to bioremediation involves multidisciplinary approach include biostimulation where organisms selected for high degradation abilities are used to inoculate the contaminated site, bioaugmentation adding microorganisms that naturally contain catabolic genes, bioaccumulation this process requires live cells, biosorption where metal sorption to cell surface by physicochemical mechanisms and phytoremediation use of plants to concentrate and metabolize toxic compounds in contaminated sites. During bioremediation, bacteria utilized for metal removal from contaminated sites is also a promising technology. However, the bacterial or plant-based processes may include the large volumes of production based on pollutant-loaded biomass, which is problematic disposal. Accordingly, in the current scenario, biological methods, i.e. bacterial mediated bioremediation, have the upper hand in terms of sustainability and easy applicability in-situ. The development of genetic engineering has given us the substantial knowledge of molecular biology and biochemistry has also led to the development of efficient techniques to monitor the fate of genetically engineered microorganisms (GEMs) upon release into the environment. Genetically modification technique has resulted often in a wide variety of current and promising applications for use in the process of bioremediation. Today, genetically modified microorganisms have found applications in human health, agriculture, and bioremediation and in industries such as food, paper, and textiles. Genetic engineering offers the advantages over traditional methods of increasing molecular diversity and improving chemical selectivity. GEMs have the possible to be a persuasive tool for cleaning up certain kinds of environmental contamination. This present discussion delineates several molecular tools and strategies to engineer microorganisms; the advantages and limitations of the methods are addressed. The final part of this chapter reviews and evaluates several applications of GEMs currently employed in commercial ventures.