97
4.5.4 Genetically Modified Bacterial Biosensor in Pesticides
Pesticides are synthetic organic compounds, and EPA restricts application of many
pesticides (Endosulfan) due to environmental concern and human health. The recalcitrance of pesticides causes serious problems. It leads to immunotoxicity, carcinogenicity, and damage to hormonal imbalance. Pesticides have been detected in soil,
water, and surface sediments. Serdar et al. (1989) detected organophosphorus pesticides using genetically engineered E. coli harbouring the organophosphorus degradation gene of Pseudomonas putida. A whole-cell electrochemical biosensor was
developed for detection of organochlorine pesticide using pulsed amperometry with
a detection limit of 2 ppt (Prathap et al. 2012). By the expression of linA2 gene
encoding the γ-hexachloro cyclohexane dehydrochlorinase from Sphingomonas
paucimobilis, lindane was degraded with the associated generation of hydrochloric
acid in E. coli immobilized on a polyaniline film. This electrochemical biosensor
provides a more suitable platform for on-site monitoring of environmental samples
as purified γ-hexachlorocyclohexane dehydrochlorinase that is likely to be inhibited
by several physicochemical factors such as organophosphate pesticides. In another
study, Kim et al. (2013) developed a biosensor for monitoring paraoxon. This sensor
system showed long-term stability (28 days) with 80% retained activity and reusability for up to 20 times. Several evidences confirmed the sensitivity of genetically
modified microbial biosensors toward environmentally toxic compounds.
4.6 Genetically Engineered Bacterial Biosensor for Heavy
Metal Detection
Industrial and human activities are increasing the heavy metals (atomic weight
between 63.5 and 200.6 g mol
−1
and a specific gravity greater than 5 g cm
−3
are
called as heavy metals) in the environment; Cd, Hg, and lead (Pb) are of considerable interest due to their toxicity and pollution issue.
A sensor plasmid was constructed by inserting the regulation unit to control the
expression of reporter gene. Modified Staphylococcus aureus strain RN4220
(pTOO24) mainly responded to cadmium, lead, and antimony. The detection limit
reached up to 10 nM, 33 nM and 1 nM, respectively. Modified Bacillus subtilis
strain BR151 (pTOO24) responds to Cd, antimony, zinc, and tin. The response was
achieved with 2–3 h incubation (Tauriainen et al. 1998). Further, Ivask et al. (2004)
constructed a biosensor to examine the bioavailability of Cd and Pb in soil. In this
work, they have constructed two recombinant bacterial biosensors (lux used as
reporter gene) for identifying Cd and Pb in agricultural soils nearby metal smelter
4 Genetically Modified Microbial Biosensor for Detection of Pollutants in Water…
4.5.4 Genetically Modified Bacterial Biosensor in Pesticides
Pesticides are synthetic organic compounds, and EPA restricts application of many
pesticides (Endosulfan) due to environmental concern and human health. The recalcitrance of pesticides causes serious problems. It leads to immunotoxicity, carcinogenicity, and damage to hormonal imbalance. Pesticides have been detected in soil,
water, and surface sediments. Serdar et al. (1989) detected organophosphorus pesticides using genetically engineered E. coli harbouring the organophosphorus degradation gene of Pseudomonas putida. A whole-cell electrochemical biosensor was
developed for detection of organochlorine pesticide using pulsed amperometry with
a detection limit of 2 ppt (Prathap et al. 2012). By the expression of linA2 gene
encoding the γ-hexachloro cyclohexane dehydrochlorinase from Sphingomonas
paucimobilis, lindane was degraded with the associated generation of hydrochloric
acid in E. coli immobilized on a polyaniline film. This electrochemical biosensor
provides a more suitable platform for on-site monitoring of environmental samples
as purified γ-hexachlorocyclohexane dehydrochlorinase that is likely to be inhibited
by several physicochemical factors such as organophosphate pesticides. In another
study, Kim et al. (2013) developed a biosensor for monitoring paraoxon. This sensor
system showed long-term stability (28 days) with 80% retained activity and reusability for up to 20 times. Several evidences confirmed the sensitivity of genetically
modified microbial biosensors toward environmentally toxic compounds.
4.6 Genetically Engineered Bacterial Biosensor for Heavy
Metal Detection
Industrial and human activities are increasing the heavy metals (atomic weight
between 63.5 and 200.6 g mol
−1
and a specific gravity greater than 5 g cm
−3
are
called as heavy metals) in the environment; Cd, Hg, and lead (Pb) are of considerable interest due to their toxicity and pollution issue.
A sensor plasmid was constructed by inserting the regulation unit to control the
expression of reporter gene. Modified Staphylococcus aureus strain RN4220
(pTOO24) mainly responded to cadmium, lead, and antimony. The detection limit
reached up to 10 nM, 33 nM and 1 nM, respectively. Modified Bacillus subtilis
strain BR151 (pTOO24) responds to Cd, antimony, zinc, and tin. The response was
achieved with 2–3 h incubation (Tauriainen et al. 1998). Further, Ivask et al. (2004)
constructed a biosensor to examine the bioavailability of Cd and Pb in soil. In this
work, they have constructed two recombinant bacterial biosensors (lux used as
reporter gene) for identifying Cd and Pb in agricultural soils nearby metal smelter
4 Genetically Modified Microbial Biosensor for Detection of Pollutants in Water…