water sample become attached to the immobilized antibodies, and the change in
impedance caused by the bacteria is measured over a frequency range of 100 Hz–
10 MHz. Heijnen and Medema [18] also developed a rapid real-time NASBA
method for the detection of E. coli in water. In their method, a fragment of the
clpB-mRNA is amplified, and a specific molecular beacon probe is used to detect
the amplified mRNA fragment during the NASBA reaction. This method can
produce results within 3–4 h. These studies demonstrate that the NASBA method
has high potential as a rapid test for microbiological water quality monitoring.
Nanotechnology has opened new avenues of research for early warning and
detecting pathogens in water. In the United States, NASA’s exploratory efforts to
detect water and biological traces on the planet Mars have delivered important
discoveries that are applicable to developing ultrasensitive biosensors [19]. The
major components of the biosensor are carbon nanotubes: tubes of graphite about
1/50,000th the diameter of a human hair. These biosensors use nucleic acids bound
to E. coli or other pathogens of interest to create an electrical change and send a
signal. Early Warning, Inc., a spin-off from NASA’s Research Center, has developed a working version of the NASA biosensor calibrated to detect the bacteria
strain E. coli O157:H7 in water, and its commercial Biohazard Water Analyzer can
be configured to test for a suite of waterborne pathogens including E. coli, Cryptosporidium, Giardia, and other bacteria, viruses, and parasitic protozoa. The
biosensor operates in the field via a wired or wireless network allowing for rapid
detection of pathogenic contaminants [19].
3.4.2 Toxin Detection
Microorganisms are increasingly used as specific devices for sensing biologically
relevant concentrations of pollutants [20]. For example, Fiorentino et al. [21]
developed a whole-cell bacterial biosensor for measuring aqueous concentrations
of aromatic aldehydes.
Recent research exploits the known characteristics of photosystems, which
convert light energy into chemical energy, to detect changes in the process of
photosynthesis of algae in water under environmental stress. Algae are sensitive
to toxins in water. Using chlorophyll, a biological molecule found in photosynthetic
organisms such as algae, fluorescence to detect toxins in water is a relatively new
idea. The chlorophyll fluorescence detection provides information about the efficiency of photosynthesis as well as insight on how tolerant the organism is under
certain environmental stresses and the effect of those stresses on the photosynthetic
process.
Researchers at the Oak Ridge National Laboratory (ORNL) in the United States
have utilized naturally free-living algae in water to investigate the impact on the
chlorophyll fluorescence produced by algae in the presence of the chemicals
[22]. Results are reported for paraquat, methyl parathion, potassium cyanide,
diuron, and atrazine concentrations in water. The study shows that algae are capable
of detecting very minute concentrations of the toxins in water.
194
T. Younos and C.J. Heyer
impedance caused by the bacteria is measured over a frequency range of 100 Hz–
10 MHz. Heijnen and Medema [18] also developed a rapid real-time NASBA
method for the detection of E. coli in water. In their method, a fragment of the
clpB-mRNA is amplified, and a specific molecular beacon probe is used to detect
the amplified mRNA fragment during the NASBA reaction. This method can
produce results within 3–4 h. These studies demonstrate that the NASBA method
has high potential as a rapid test for microbiological water quality monitoring.
Nanotechnology has opened new avenues of research for early warning and
detecting pathogens in water. In the United States, NASA’s exploratory efforts to
detect water and biological traces on the planet Mars have delivered important
discoveries that are applicable to developing ultrasensitive biosensors [19]. The
major components of the biosensor are carbon nanotubes: tubes of graphite about
1/50,000th the diameter of a human hair. These biosensors use nucleic acids bound
to E. coli or other pathogens of interest to create an electrical change and send a
signal. Early Warning, Inc., a spin-off from NASA’s Research Center, has developed a working version of the NASA biosensor calibrated to detect the bacteria
strain E. coli O157:H7 in water, and its commercial Biohazard Water Analyzer can
be configured to test for a suite of waterborne pathogens including E. coli, Cryptosporidium, Giardia, and other bacteria, viruses, and parasitic protozoa. The
biosensor operates in the field via a wired or wireless network allowing for rapid
detection of pathogenic contaminants [19].
3.4.2 Toxin Detection
Microorganisms are increasingly used as specific devices for sensing biologically
relevant concentrations of pollutants [20]. For example, Fiorentino et al. [21]
developed a whole-cell bacterial biosensor for measuring aqueous concentrations
of aromatic aldehydes.
Recent research exploits the known characteristics of photosystems, which
convert light energy into chemical energy, to detect changes in the process of
photosynthesis of algae in water under environmental stress. Algae are sensitive
to toxins in water. Using chlorophyll, a biological molecule found in photosynthetic
organisms such as algae, fluorescence to detect toxins in water is a relatively new
idea. The chlorophyll fluorescence detection provides information about the efficiency of photosynthesis as well as insight on how tolerant the organism is under
certain environmental stresses and the effect of those stresses on the photosynthetic
process.
Researchers at the Oak Ridge National Laboratory (ORNL) in the United States
have utilized naturally free-living algae in water to investigate the impact on the
chlorophyll fluorescence produced by algae in the presence of the chemicals
[22]. Results are reported for paraquat, methyl parathion, potassium cyanide,
diuron, and atrazine concentrations in water. The study shows that algae are capable
of detecting very minute concentrations of the toxins in water.
194
T. Younos and C.J. Heyer