samples. UV-killed hantavirus strains were studied as dilutions on slides, and it was
also found possible to differentiate between strains. Jonathan and Pourmand (2007)
also identified and compared a pathogenic with nonpathogenic strain by LIBS. In
their experiment they identified a pathogenic strain of bacteria, Escherichia coli
O157:H7 enterohemorrhagic E. coli or EHEC, and compared three nonpathogenic E.
coli strains (a laboratory strain of K-12 AB), a derivative of the same strain termed
HF4714, by LIBS with nanosecond pulses in environmental samples. Multari et al.
(2012) described the rapid detection of biological contaminants, such as Escherichia
coli O157:H7 and Salmonella enterica, on perishable foods items present in environment. Here, multivariate regression analysis of LIBS data is used to differentiate
the live bacterial pathogens E. coli O157:H7 and S. enterica in various foods
(eggshell, milk, bologna, ground beef, chicken, and lettuce) and surfaces (metal
drain strainer and cutting board). Qassem et al. (2011) investigated the effect that
adverse environmental and metabolic stresses have on the laser-induced breakdown
spectroscopy (LIBS) identification of bacterial specimens. Single-pulse LIBS spectra were acquired from a nonpathogenic strain of Escherichia coli cultured in two
different nutrient media: a trypticase soy agar and a MacConkey agar with a 0.01%
concentration of deoxycholate. A chemometric discriminant function analysis
showed that the LIBS spectra acquired from bacteria grown in these two media
were indistinguishable and easily discriminated from spectra acquired from two
other nonpathogenic E. coli strains. Samuels et al. (2003) also used laser-induced
breakdown spectroscopy to study bacterial spores, molds, pollens, and proteins.
Biosamples were prepared and deposited onto porous silver substrates. LIBS data
from the individual laser shots were analyzed by principal components analysis and
were found to contain adequate information to afford discrimination among the
different biomaterials.
9.2.4 Need of Sensors
Environmental pollution in various media is a serious health concern worldwide.
Hence there is a continuing need to develop a cost-effective, accurate, fast, reliable,
noninvasive, and nondestructive methods or tools for fast, analytical techniques used
in comprehensive monitoring programs. Humans have sensors to understand and
detect the environment around them. Therefore, it is equally important to design and
develop biosensor-based measurement techniques that can accurately detect various
contaminants from a wide spectrum. However, biosensors have several limitations
for environmental analysis including (1) response time, (2) sensitivity, (3) selectivity,
(4) compatibility, (5) affinity, (6) stability, (7) lifetime, etc.
9.2.4.1 Biological Sensor
A biosensor is a device that can be used to convert the existence of a molecule or
compound into a measurable and useful signal. Biosensors use excitation to translate
changes into recognizable signals. In 1962 Clark and Lyons developed a fast and
more precise biosensor for glucose measurement. Biological sensors are analytical
9 Development of Modern Tools for Environmental Monitoring of Pathogens and. . .
197
also found possible to differentiate between strains. Jonathan and Pourmand (2007)
also identified and compared a pathogenic with nonpathogenic strain by LIBS. In
their experiment they identified a pathogenic strain of bacteria, Escherichia coli
O157:H7 enterohemorrhagic E. coli or EHEC, and compared three nonpathogenic E.
coli strains (a laboratory strain of K-12 AB), a derivative of the same strain termed
HF4714, by LIBS with nanosecond pulses in environmental samples. Multari et al.
(2012) described the rapid detection of biological contaminants, such as Escherichia
coli O157:H7 and Salmonella enterica, on perishable foods items present in environment. Here, multivariate regression analysis of LIBS data is used to differentiate
the live bacterial pathogens E. coli O157:H7 and S. enterica in various foods
(eggshell, milk, bologna, ground beef, chicken, and lettuce) and surfaces (metal
drain strainer and cutting board). Qassem et al. (2011) investigated the effect that
adverse environmental and metabolic stresses have on the laser-induced breakdown
spectroscopy (LIBS) identification of bacterial specimens. Single-pulse LIBS spectra were acquired from a nonpathogenic strain of Escherichia coli cultured in two
different nutrient media: a trypticase soy agar and a MacConkey agar with a 0.01%
concentration of deoxycholate. A chemometric discriminant function analysis
showed that the LIBS spectra acquired from bacteria grown in these two media
were indistinguishable and easily discriminated from spectra acquired from two
other nonpathogenic E. coli strains. Samuels et al. (2003) also used laser-induced
breakdown spectroscopy to study bacterial spores, molds, pollens, and proteins.
Biosamples were prepared and deposited onto porous silver substrates. LIBS data
from the individual laser shots were analyzed by principal components analysis and
were found to contain adequate information to afford discrimination among the
different biomaterials.
9.2.4 Need of Sensors
Environmental pollution in various media is a serious health concern worldwide.
Hence there is a continuing need to develop a cost-effective, accurate, fast, reliable,
noninvasive, and nondestructive methods or tools for fast, analytical techniques used
in comprehensive monitoring programs. Humans have sensors to understand and
detect the environment around them. Therefore, it is equally important to design and
develop biosensor-based measurement techniques that can accurately detect various
contaminants from a wide spectrum. However, biosensors have several limitations
for environmental analysis including (1) response time, (2) sensitivity, (3) selectivity,
(4) compatibility, (5) affinity, (6) stability, (7) lifetime, etc.
9.2.4.1 Biological Sensor
A biosensor is a device that can be used to convert the existence of a molecule or
compound into a measurable and useful signal. Biosensors use excitation to translate
changes into recognizable signals. In 1962 Clark and Lyons developed a fast and
more precise biosensor for glucose measurement. Biological sensors are analytical
9 Development of Modern Tools for Environmental Monitoring of Pathogens and. . .
197