Utilization of genetically engineered microorganisms (GEMs) for bioremediation

Abstract

The wide metabolic and physiological versatility of microorganisms can be used to degrade many pollutants. Bioremediation is the technological process whereby biological systems are harnessed to effect the clean-up of environmental pollutants. Nowadays, microbial systems are employed in bioremediation programmes, generally in the treatment of soils and waters contaminated with organic pollutants. There are instances where natural populations are not suitable for use in the remediation of polluted sites and therefore the utilization of genetically engineered microorganisms (GEMs) is being considered for in-situ bioremediation of contaminated ecosystems. The deliberate release of GEMs into the environment is a subject of considerable public concern. The potential risks associated with the release of GEMs into the environment has led to the construction of biological containment systems by which bacteria are killed in a controlled suicide process. Active biological containment systems usually consist of two different components, a killing element designed to induce cell death and a control element which modulates the expression of the killing function.

Recent Advances in Petroleum Microbiology

“…We are learning a great deal about cellular and other physiological adaptations to the presence of hydrocarbons, as well as the biochemical mechanisms involved in hydrocarbon accession and uptake (143,251,566). The use of genetically engineered microbes for bioremediation has also been considered (210).…”

Microbial communities to mitigate contamination of PAHs in soil—possibilities and challenges: a review

“…Bioremediation is the process by which living organisms degrade or transform hazardous organic contaminants to inorganic components, such as CO 2 , H 2 O, and NO 3 − (Garbisu and Alkorta 1999;Paul et al 2005a), which are also produced during the mineralization of organic matter in soil. A number of processes upstream of the biocatalysis, e.g., diffusion in solid matrixes, bioavailability, weathering and abiotic catalysis of pollutants, and downstream, e.g., stress, predation, and competition, are known to constrain the process ( de Lorenzo 2008).…”

“…There are microorganisms with a wide metabolic and physiological versatility, which can be used to degrade PAHs (Garbisu and Alkorta 1999). Nevertheless, there are microorganisms without the capacity to dissipate PAHs from soil, but with other interesting characteristics, such as to survive extreme conditions.…”

“…The risks associated with uncontrolled growth and proliferation of GEMs and horizontal gene transfer may be minimized through rapid death after dissipation of the PAHs. It is therefore better to consider the use of engineered survival-deficient organisms, such as those obtained using suicide systems, rather than persistent strains (Molin et al 1993;Garbisu and Alkorta 1999). Therefore, the inclusion of a containment system for the limited survival of the engineered organisms in situ might be required (Paul et al 2005b).…”

Dehalogenation of 4 — Chlorobenzoic Acid by Pseudomonas isolates

“…Xenobiotics frequently include unusual chemical bonds or substitution with halogens or other functional groups that can render a molecule highly resistant to degradation 7 . Luckily, by means of exploiting the metabolic versatility and catabolic abilities of microorganism, it has been possible to transform the contaminants into less harmful end products, which are then integrated into natural biogeochemical cycles [8][9] . Bioremediation offers a potentially more effective and economical cleanup technique than conventional physicochemical methods.…”