8 New Developments in Metal Bioremediation
With the increasing global population, fast-tracked industrialization, and discovery
of new technologies, the volume and complexity of metal pollution is bound to
increase in the future. In addition to the increasing trajectory in the generation of
conventional metallic pollutants, future energy demands may result in a transitional
period where nuclear energy will become predominant. This will require environmental engineers and scientist to delve deeper into research on environmentally
friendly processes to counter the effects of both conventional and nonconventional
pollutants such as heavy metals and recalcitrant organic compounds in the environment. Advanced microbial cultures will be sought to treat a wider variety of
recalcitrant pollutants. Discussions on the possibility of genetically engineering
specialized cultures for the purpose are not new in the environmental engineering
fraternity. However, the application of ideas bears a large ethical burden as it is
forbidden in almost all countries in the world to introduce genetically engineered
organisms into the environment. Less aggressive methods for dealing with the
problem without violating ethics include in situ bioaugmentation and molecular
bioaugmentation to a certain extent.
8.1 Molecular Bioaugmentation
The molecular bioaugmentation process utilized genetic carriers such as transposons
and plasmids to shuttle genetic information for toxic metal remediation into native
species to the environment or species already adapted to the target environment.
Several species of bacteria are capable of picking up and retaining circular fragments
of DNA called broad-host-range plasmids which may be engineered to carry specific
genes for the degradation of xenobiotic compounds and transformation of toxic
metals (Weightman et al. 1984; Vincze and Bowra 2006). The same process can be
applied using genetically engineered linear DNA called transposons. Although
studies have been conducted using these techniques in laboratory microcosms, the
application in actual environments has not been attempted (Hill et al. 1994). In the
future, it is foreseeable that these methods will find wide application for the new
pollutant varieties that may be untreatable by conventional methods.
8.2 Biofractionation and Bioseparation of Radioactive
Elements
A very little understood application of bioseparation involves using microorganisms
to discriminate radioisotopes by size. So far, this application has remained conceptual due to limited understanding on the structure and function of organisms that are
2 Advances in Bioremediation of Toxic Heavy Metals and Radionuclides in. . .
43
With the increasing global population, fast-tracked industrialization, and discovery
of new technologies, the volume and complexity of metal pollution is bound to
increase in the future. In addition to the increasing trajectory in the generation of
conventional metallic pollutants, future energy demands may result in a transitional
period where nuclear energy will become predominant. This will require environmental engineers and scientist to delve deeper into research on environmentally
friendly processes to counter the effects of both conventional and nonconventional
pollutants such as heavy metals and recalcitrant organic compounds in the environment. Advanced microbial cultures will be sought to treat a wider variety of
recalcitrant pollutants. Discussions on the possibility of genetically engineering
specialized cultures for the purpose are not new in the environmental engineering
fraternity. However, the application of ideas bears a large ethical burden as it is
forbidden in almost all countries in the world to introduce genetically engineered
organisms into the environment. Less aggressive methods for dealing with the
problem without violating ethics include in situ bioaugmentation and molecular
bioaugmentation to a certain extent.
8.1 Molecular Bioaugmentation
The molecular bioaugmentation process utilized genetic carriers such as transposons
and plasmids to shuttle genetic information for toxic metal remediation into native
species to the environment or species already adapted to the target environment.
Several species of bacteria are capable of picking up and retaining circular fragments
of DNA called broad-host-range plasmids which may be engineered to carry specific
genes for the degradation of xenobiotic compounds and transformation of toxic
metals (Weightman et al. 1984; Vincze and Bowra 2006). The same process can be
applied using genetically engineered linear DNA called transposons. Although
studies have been conducted using these techniques in laboratory microcosms, the
application in actual environments has not been attempted (Hill et al. 1994). In the
future, it is foreseeable that these methods will find wide application for the new
pollutant varieties that may be untreatable by conventional methods.
8.2 Biofractionation and Bioseparation of Radioactive
Elements
A very little understood application of bioseparation involves using microorganisms
to discriminate radioisotopes by size. So far, this application has remained conceptual due to limited understanding on the structure and function of organisms that are
2 Advances in Bioremediation of Toxic Heavy Metals and Radionuclides in. . .
43