based on specifically modified Saccharomyces cerevisiae strain immobilized in
alginate beads. This biosensor was capable of detecting copper ions at concentrations of 1–100 lM. The biosensor beads change color to white, when copper is
present in concentrations below the detection limit, while increase in copper concentration is determined by pink or red color. The biosensor was successfully tested
to determine copper concentrations in copper contaminated water samples. When
compared to other fluorescent protein based biosensors or analytical methods, the
developed biosensor did not required specific equipment and facilitated rapid
detection of copper in parallel samples.
In their research, Ponamoreva et al. [66], used methylotrophic Pichia angusta
and oleaginous Cryptococcus curvatus yeast cells immobilized in a bimodal
silica-organic sol–gel matrix with tetraethoxysilane (TEOS), methyltriethoxysilane
(MTES) as hydrophobic additive and polyethylene glycol (PEG) as the porogen for
pollutant monitoring. Under controlled experimental conditions and catalysts, yeast
cells formed nucleation centers for a silica-organic capsule fabricated over cells.
Effect of MTES composition on the nature of encapsulated yeast cells together with
the architecture of the three-dimensional sol-gel biomatrix formation during the
encapsulation was well demonstrated. Each yeast cell was examined and detected as
to be encapsulated by silica when 85 vol.% MTES was used. These silica capsules
were found to protect microorganisms from harmful exposure of heavy metal and
UV radiation. P. angusta cells were used in biosensors for the detection of
methanol.
Microbial cultures were mixed and co-cultures were created to develop the
receptor element of a biosensor for assessment of biological oxygen demand
(BOD). These co-cultures had broad substrate specificities and enabled water and
fermentation product assays within a broad BOD range (2.4–80 mg/dm
3 ). Use of
the co-cultures constituting yeasts Pichia angusta, Arxula adeninivorans and
Debaryomyces hansenii immobilized in N-vinylpyrrolidone-modified poly (vinyl
alcohol) resulted in a BOD biosensor possessing the characteristics not inferior to
those in the known biosensors. The results indicated potential use of these
co-cultures as the receptor element base for broad application in prototype instruments [93]. Kim et al. [48, 49] designed a whole cell array biosensor for the
effective detection and monitoring of neurotoxic organophosphate compounds. In
2012, Jouanneau et al. [45, 46] skillfully demonstrated use of two varieties of
biosensors (Lumisens III and Lumisens IV) for on-line detection of heavy metals in
environmental samples, based on different storage modes of luminescent bacteria.
Bacterial suspension was staged in a micro-well driven by continuous flow with 4%
agarose solution in Lumisens III system having a higher biological activity. Freeze
dried bacteria in 96-well microplates were used in Lumisens IV system having
relatively low biological activity. Both systems were enclosed in the dark chamber,
and the light signals emitted by bacteria were captured and recorded by CCD
camera. In 10 days, the two biosensors were used to continuously detect mercury
(Hg) in distilled water and environmental samples. Kolahchi et al. [51] developed a
Materials in Emerging Water Pollutants Detection
267
alginate beads. This biosensor was capable of detecting copper ions at concentrations of 1–100 lM. The biosensor beads change color to white, when copper is
present in concentrations below the detection limit, while increase in copper concentration is determined by pink or red color. The biosensor was successfully tested
to determine copper concentrations in copper contaminated water samples. When
compared to other fluorescent protein based biosensors or analytical methods, the
developed biosensor did not required specific equipment and facilitated rapid
detection of copper in parallel samples.
In their research, Ponamoreva et al. [66], used methylotrophic Pichia angusta
and oleaginous Cryptococcus curvatus yeast cells immobilized in a bimodal
silica-organic sol–gel matrix with tetraethoxysilane (TEOS), methyltriethoxysilane
(MTES) as hydrophobic additive and polyethylene glycol (PEG) as the porogen for
pollutant monitoring. Under controlled experimental conditions and catalysts, yeast
cells formed nucleation centers for a silica-organic capsule fabricated over cells.
Effect of MTES composition on the nature of encapsulated yeast cells together with
the architecture of the three-dimensional sol-gel biomatrix formation during the
encapsulation was well demonstrated. Each yeast cell was examined and detected as
to be encapsulated by silica when 85 vol.% MTES was used. These silica capsules
were found to protect microorganisms from harmful exposure of heavy metal and
UV radiation. P. angusta cells were used in biosensors for the detection of
methanol.
Microbial cultures were mixed and co-cultures were created to develop the
receptor element of a biosensor for assessment of biological oxygen demand
(BOD). These co-cultures had broad substrate specificities and enabled water and
fermentation product assays within a broad BOD range (2.4–80 mg/dm
3 ). Use of
the co-cultures constituting yeasts Pichia angusta, Arxula adeninivorans and
Debaryomyces hansenii immobilized in N-vinylpyrrolidone-modified poly (vinyl
alcohol) resulted in a BOD biosensor possessing the characteristics not inferior to
those in the known biosensors. The results indicated potential use of these
co-cultures as the receptor element base for broad application in prototype instruments [93]. Kim et al. [48, 49] designed a whole cell array biosensor for the
effective detection and monitoring of neurotoxic organophosphate compounds. In
2012, Jouanneau et al. [45, 46] skillfully demonstrated use of two varieties of
biosensors (Lumisens III and Lumisens IV) for on-line detection of heavy metals in
environmental samples, based on different storage modes of luminescent bacteria.
Bacterial suspension was staged in a micro-well driven by continuous flow with 4%
agarose solution in Lumisens III system having a higher biological activity. Freeze
dried bacteria in 96-well microplates were used in Lumisens IV system having
relatively low biological activity. Both systems were enclosed in the dark chamber,
and the light signals emitted by bacteria were captured and recorded by CCD
camera. In 10 days, the two biosensors were used to continuously detect mercury
(Hg) in distilled water and environmental samples. Kolahchi et al. [51] developed a
Materials in Emerging Water Pollutants Detection
267