the metabolic pathway. GEMs are generated through hybrid gene clusters which
modify activities of enzymes as well as enzyme substrate specificities. These gene
clusters code for the enzyme with better transforming capacity. By genetically
modifying E. coli strain, a hybrid gene cluster for degrading trichloroethylene
(TCE) is expressed.
In the fourth strategy, bioprocess development, its observation and regulation as
well as bioaffinity, bioreporter, sensor usage for chemical sensing, decrease in
toxicity, and end-point analysis is performed. There are fewer reports on this
strategy. However, a lux gene-based system has been developed which has many
benefits to monitor bioremediation methods. Bioluminescence is very easy to detect
and has no need for costly instruments, additional chemicals or co-factors from
outside. GEMs also have chemical sensors which permit the observation of bioavailability of pollutants rather than just their presence. GEMs generated by bioluminescence assist in gaining knowledge about the microbes present in the region of
contamination as well as of the last stage of bioremediation.
To overcome the restrictions of usage of wild-type microbes, various
developments in GEMs have been done. Microbes cannot be used in anaerobic
conditions as they are limited to aerobic catabolic as well as co-metabolic pathways.
To utilize them in an anaerobic environment, production of GEMs through the
incorporation of genes for oxygenases is done. Before using microbes for bioremediation, each and every xenobiotic existing in a multi-contaminated environment
should be considered. Because of incorporating various genes from different
microbes in a single microorganism, GEMs attain diverse characters which can be
utilized effectively for bioremediation. But, it is highly important to take precautions
for the safety of the environment as well as human health during the application of
GEMs for remediating contaminants. Those microbes or GEMs that utilize
xenobiotics as a source of carbon, energy and/or nitrogen can obtain nutrients and
flourish there. In fact, they may scatter in an uninhibited way which may prove
harmful. Scientists have developed a new approach for “suicidal genetically
engineered
microorganisms
(SGEMs)”
through
searching
antisense
RNA-controlled plasmid dependence, proteic plasmid dependence and inducible
bacterial degradative operons. For designing new S-GEM, information on killer–
anti-killer genes is required to create microbes prone to programmed cell death
following xenobiotic degradation. This technology assists in eliminating microbes
just after bioremediation through autolysis and thus decrease the dangers for human
beings and environment.
Usage of GEM-dependent xenobiotic remediation is in the front because it is an
environmental and human-friendly strategy. But, production of GEMs is not much
because of the restricted knowledge about the genes. A second major hurdle in the
implementation of GEM is its controlling measures and related risks. Although this
problem can be solved through the production and utilization of suicidal genetically
engineered microorganisms. In future, this can become a highly effective technique
if we acquire the knowledge about microbes as bioremediating devices, their
genomes and biochemical mechanism exercises. This will permit the usage of
344
N. Srivastava
modify activities of enzymes as well as enzyme substrate specificities. These gene
clusters code for the enzyme with better transforming capacity. By genetically
modifying E. coli strain, a hybrid gene cluster for degrading trichloroethylene
(TCE) is expressed.
In the fourth strategy, bioprocess development, its observation and regulation as
well as bioaffinity, bioreporter, sensor usage for chemical sensing, decrease in
toxicity, and end-point analysis is performed. There are fewer reports on this
strategy. However, a lux gene-based system has been developed which has many
benefits to monitor bioremediation methods. Bioluminescence is very easy to detect
and has no need for costly instruments, additional chemicals or co-factors from
outside. GEMs also have chemical sensors which permit the observation of bioavailability of pollutants rather than just their presence. GEMs generated by bioluminescence assist in gaining knowledge about the microbes present in the region of
contamination as well as of the last stage of bioremediation.
To overcome the restrictions of usage of wild-type microbes, various
developments in GEMs have been done. Microbes cannot be used in anaerobic
conditions as they are limited to aerobic catabolic as well as co-metabolic pathways.
To utilize them in an anaerobic environment, production of GEMs through the
incorporation of genes for oxygenases is done. Before using microbes for bioremediation, each and every xenobiotic existing in a multi-contaminated environment
should be considered. Because of incorporating various genes from different
microbes in a single microorganism, GEMs attain diverse characters which can be
utilized effectively for bioremediation. But, it is highly important to take precautions
for the safety of the environment as well as human health during the application of
GEMs for remediating contaminants. Those microbes or GEMs that utilize
xenobiotics as a source of carbon, energy and/or nitrogen can obtain nutrients and
flourish there. In fact, they may scatter in an uninhibited way which may prove
harmful. Scientists have developed a new approach for “suicidal genetically
engineered
microorganisms
(SGEMs)”
through
searching
antisense
RNA-controlled plasmid dependence, proteic plasmid dependence and inducible
bacterial degradative operons. For designing new S-GEM, information on killer–
anti-killer genes is required to create microbes prone to programmed cell death
following xenobiotic degradation. This technology assists in eliminating microbes
just after bioremediation through autolysis and thus decrease the dangers for human
beings and environment.
Usage of GEM-dependent xenobiotic remediation is in the front because it is an
environmental and human-friendly strategy. But, production of GEMs is not much
because of the restricted knowledge about the genes. A second major hurdle in the
implementation of GEM is its controlling measures and related risks. Although this
problem can be solved through the production and utilization of suicidal genetically
engineered microorganisms. In future, this can become a highly effective technique
if we acquire the knowledge about microbes as bioremediating devices, their
genomes and biochemical mechanism exercises. This will permit the usage of
344
N. Srivastava