but also at the genetic level of the organism, to enhance enzyme production in many
different conditions (Peixoto et al. 2011). Currently, researchers can nick and insert
the appropriate genes which are responsible for the manufacturing of particular
enzymes that helps in the bioremediation of pollutants by GEMs is done through
four activities/strategies mentioned below:
1. Alteration of enzymes for their specificity and affinity.
2. Pathways for construction as well as regulation.
3. Bioprocess development followed by the process of regulation and monitoring.
4. Bioaffinity bioreporting sensor applications for sensing of chemicals, reducing
toxicity and analysis of endpoint (Abatenh et al. 2017).
Genes responsible for bioremediation of harmful contaminants such as toluene,
chlorobenzene acids, pesticides that are halogenated and toxic wastes are reported.
For every chemical, one individual plasmid is required because; a single plasmid can
biodegrade all the harmful compounds of different types. The plasmids are placed
under four subcategories:
1. OCT plasmid that biodegrades: decane, hexane and octane.
2. XYL plasmid which biodegrades toluene and xylene.
3. CAM plasmid that decomposes camphor.
4. NAH plasmid which biodegrades naphthalene (Joutey et al. 2013).
The bacteria named Deinococcus radioduransis, a radioactive resistant organism,
had been modified for the consumption of toluene as well as ionic highly radioactive
mercury from nuclear waste (Prakash et al. 2013; Shah 2014). Recombinant
polychlorinated biphenyl (PCB)-degrading microbes with improvised stability and
survival ability in mixed populations of soil microbes is also been developed (Shah
2014). A recombinant strain of E. coli was created for biosorption ability five times
enhanced for uranium radioactive isomer by changing the activity of particularly
transporter genes, i.e., nixA of Helicobacter pylori and merTP of Serratia
marcescens. The family of microbe, i.e. Geobacteriaceae has, also exhibited the
ability for radioactive metal reduction (Prakash et al. 2013). Engineered
Deinococcus geothermalis strains have been made for the biodegradation of the
environment carrying a mixture of radioactive waste at high temperatures. A recombinant strain of Acenitobacterbaumanii was noticed to improve rates of biodegradation of crude oil-polluted sites (Coelho et al. 2015). Numerous strains of
Mycobacterium marinu, Sphingomonas desiccabilis, Ralstonia eutropha,
P. putida, E. coli and B. idriensis etc. have the genes that are integrated into their
genomes, which help in biodegradation of hazardous metal compounds present in
polluted surroundings. Further, the potential of the recombinant strain B3 of
Mesorhizobium huakuii subsp. Rengei for the production of phytochelatins (PCs)
and accumulation of cadmium Cd
2+ is enhanced. These modified strains of bacteria
are advantageous for the production of a newer plant–bacterium-mediated biodegradation system to remove heavy metals from rice crops when genetically engineered
442
G. Kaur et al.
different conditions (Peixoto et al. 2011). Currently, researchers can nick and insert
the appropriate genes which are responsible for the manufacturing of particular
enzymes that helps in the bioremediation of pollutants by GEMs is done through
four activities/strategies mentioned below:
1. Alteration of enzymes for their specificity and affinity.
2. Pathways for construction as well as regulation.
3. Bioprocess development followed by the process of regulation and monitoring.
4. Bioaffinity bioreporting sensor applications for sensing of chemicals, reducing
toxicity and analysis of endpoint (Abatenh et al. 2017).
Genes responsible for bioremediation of harmful contaminants such as toluene,
chlorobenzene acids, pesticides that are halogenated and toxic wastes are reported.
For every chemical, one individual plasmid is required because; a single plasmid can
biodegrade all the harmful compounds of different types. The plasmids are placed
under four subcategories:
1. OCT plasmid that biodegrades: decane, hexane and octane.
2. XYL plasmid which biodegrades toluene and xylene.
3. CAM plasmid that decomposes camphor.
4. NAH plasmid which biodegrades naphthalene (Joutey et al. 2013).
The bacteria named Deinococcus radioduransis, a radioactive resistant organism,
had been modified for the consumption of toluene as well as ionic highly radioactive
mercury from nuclear waste (Prakash et al. 2013; Shah 2014). Recombinant
polychlorinated biphenyl (PCB)-degrading microbes with improvised stability and
survival ability in mixed populations of soil microbes is also been developed (Shah
2014). A recombinant strain of E. coli was created for biosorption ability five times
enhanced for uranium radioactive isomer by changing the activity of particularly
transporter genes, i.e., nixA of Helicobacter pylori and merTP of Serratia
marcescens. The family of microbe, i.e. Geobacteriaceae has, also exhibited the
ability for radioactive metal reduction (Prakash et al. 2013). Engineered
Deinococcus geothermalis strains have been made for the biodegradation of the
environment carrying a mixture of radioactive waste at high temperatures. A recombinant strain of Acenitobacterbaumanii was noticed to improve rates of biodegradation of crude oil-polluted sites (Coelho et al. 2015). Numerous strains of
Mycobacterium marinu, Sphingomonas desiccabilis, Ralstonia eutropha,
P. putida, E. coli and B. idriensis etc. have the genes that are integrated into their
genomes, which help in biodegradation of hazardous metal compounds present in
polluted surroundings. Further, the potential of the recombinant strain B3 of
Mesorhizobium huakuii subsp. Rengei for the production of phytochelatins (PCs)
and accumulation of cadmium Cd
2+ is enhanced. These modified strains of bacteria
are advantageous for the production of a newer plant–bacterium-mediated biodegradation system to remove heavy metals from rice crops when genetically engineered
442
G. Kaur et al.