growth of the cell. Brim et al. (2003) have generated the close relative of the
radiation-tolerant D. radiodurans as well as D. geothermalis. It was observed that
D. geothermalis was decreasing Hg
2+ as well as Fe
3+ , U
6+ and even Cr
6+ through the
assistance of plasmids. In E. coli overexpression of nfsA reduced 1.5-fold more
chromate (Ackerley et al. 2004). Overproduction of ChrR in P. putida reduces
24 times more Cr
6+ (Gonzalez et al. 2005).
12.10.3 Pathway Switching
In pathway switching, manufacturing, expansion and control of some new genetic
processes are incorporated for bioremediation purposes. For total bioremediation of
toxic metals, an efficient method is to create a group of microbes for every particular
stage. Not much work has been done till now to improve the bacterial strains to
eliminate metals through making new consortium. The strategy of pathway
switching may be also used for eliminating metals utilizing GMOs. Because Cu–
Mb (copper–methanobactin) uptake through methanotrophic bacteria is quite obvious, a process for the uptake of Cu–Mb complexes at the same time can be
developed rather than separation of Cu from Mb before the uptake (Balasubramanian
et al. 2011). Further research in this area can be done by detecting an appropriate
pathway to acquire metals easily from the surroundings through the knowledge of
the processes of transport machineries. GMO usage for bioremediation is in front
position because of their effectiveness and low-cost strategies. But total knowledge
about the genes is needed which can be gained through microarray as well as
fluorescent in situ hybridization techniques. The risks and the control measures
linked with these organisms are certain other hurdles. Future of bacterial bioremediation depends on the production of suicidal genetically engineered microorganisms
(S-GEMs) which will increase the use of these GMOs for on-site implementations.
These S-GEMs are manufactured by utilizing a killer gene as well as controlling
circuit which regulates the expression of the killer gene against the presence or
absence of environmental indicators (Paul et al. 2005). Therefore, the manufactured
S-GEMs will have programmed cell death because of the existence of killer–antikiller genes following the elimination of harmful materials for their safe disposal in
the environment. (Das et al. 2016).
12.11 Biodegradation of Heavy Metals
Heavy metals like mercury (Hg), arsenic (As), cadmium (Cd), nickel (Ni), cobalt
(Co) and lead (Pb) are stored in the environment because of very fast industrialization and result in serious harm to the important organs in living beings (Singh et al.
2011). Detoxification mechanism of genetically modified bacteria is helpful in
bioremediation of metals. Against high Hg toxicity, the bacterial world has developed an amazing collection of tolerance processes. A group of Hg tolerance genes
(mer) in an operon promote the bacteria to transform harmful Hg
2+ into volatile Hg
12 Remediation of Heavy Metals Through Genetically Engineered Microorganism
347
radiation-tolerant D. radiodurans as well as D. geothermalis. It was observed that
D. geothermalis was decreasing Hg
2+ as well as Fe
3+ , U
6+ and even Cr
6+ through the
assistance of plasmids. In E. coli overexpression of nfsA reduced 1.5-fold more
chromate (Ackerley et al. 2004). Overproduction of ChrR in P. putida reduces
24 times more Cr
6+ (Gonzalez et al. 2005).
12.10.3 Pathway Switching
In pathway switching, manufacturing, expansion and control of some new genetic
processes are incorporated for bioremediation purposes. For total bioremediation of
toxic metals, an efficient method is to create a group of microbes for every particular
stage. Not much work has been done till now to improve the bacterial strains to
eliminate metals through making new consortium. The strategy of pathway
switching may be also used for eliminating metals utilizing GMOs. Because Cu–
Mb (copper–methanobactin) uptake through methanotrophic bacteria is quite obvious, a process for the uptake of Cu–Mb complexes at the same time can be
developed rather than separation of Cu from Mb before the uptake (Balasubramanian
et al. 2011). Further research in this area can be done by detecting an appropriate
pathway to acquire metals easily from the surroundings through the knowledge of
the processes of transport machineries. GMO usage for bioremediation is in front
position because of their effectiveness and low-cost strategies. But total knowledge
about the genes is needed which can be gained through microarray as well as
fluorescent in situ hybridization techniques. The risks and the control measures
linked with these organisms are certain other hurdles. Future of bacterial bioremediation depends on the production of suicidal genetically engineered microorganisms
(S-GEMs) which will increase the use of these GMOs for on-site implementations.
These S-GEMs are manufactured by utilizing a killer gene as well as controlling
circuit which regulates the expression of the killer gene against the presence or
absence of environmental indicators (Paul et al. 2005). Therefore, the manufactured
S-GEMs will have programmed cell death because of the existence of killer–antikiller genes following the elimination of harmful materials for their safe disposal in
the environment. (Das et al. 2016).
12.11 Biodegradation of Heavy Metals
Heavy metals like mercury (Hg), arsenic (As), cadmium (Cd), nickel (Ni), cobalt
(Co) and lead (Pb) are stored in the environment because of very fast industrialization and result in serious harm to the important organs in living beings (Singh et al.
2011). Detoxification mechanism of genetically modified bacteria is helpful in
bioremediation of metals. Against high Hg toxicity, the bacterial world has developed an amazing collection of tolerance processes. A group of Hg tolerance genes
(mer) in an operon promote the bacteria to transform harmful Hg
2+ into volatile Hg
12 Remediation of Heavy Metals Through Genetically Engineered Microorganism
347