Biomedical Engineering Reference
In-Depth Information
Lead terminal
Epoxy body
Supporter to flow cell
10 mm
SUS membrane holder
Hole for pressure balance
PTFE membrane
Au working electrode
Polypropylene net
Microbial memb ra ne
11 mm
Spacer
0.3 mm
Acetyl cellulose membrane
Microorganism
( Trichosporon cutaneum )
FIGURE 14.3 Microbial sensor for meat freshness. Microorganism: Tr ichosporon cutaneum . (From Yano,
Y., Numata, M., Hachiya, H., Ito, S., Masadome, T., Ohkubo, S., Asano, Y., and Imato, T., Talanta , 54, 255,
2001. With permission.)
Lehmann et al. [121] prepared the fi rst microbial biosensor to detect Cu 2 + by this method. The
sensor measured Cu 2 + in a concentration range between 0.5 and 2 mM CuSO 4 . In addition, they
also developed an indirect amperometric measurement principle that allows the detection of samples
containing Cu 2 + and fast biodegradable substances.
Moreover, mutants of S. cerevisiae devoid of Cu, Zn-superoxide dismutase (SOD) are hypersen-
sitive to a range of oxidants, hyperbaric oxygen, and hyperosmotic media; show lysine and methio-
nine auxotrophy when grown under the atmosphere of air; and have a shortened replicative life span
when compared with the wild-type strain. Ascorbate and other antioxidants can ameliorate these
defects [122]. Zyracka et al. [122] employed the mutant of S. cerevisiae that lacked Cu, Zn-SOD as
a tester to examine the possibility to use such yeasts for the detection of antioxidants. It is shown
that a simple plate test based on the abolishment of leucine and methionine auxotrophy of SOD-
defi cient S. cerevisiae or restoration of growth on hypertonic medium can be used for the detection
and semiquantitative estimation of concentrations of antioxidants.
14.1.2.13
Arxula adeninivorans
The yeast A. adeninivorans is found to have an amazingly broad substrate range: It assimilates
all the sugars, polyalcohols, and organic acids except for ribose, lactose, and methanol [123]. As a
result, an A. adeninivorans -based sensor should correlate with BOD 5 of most substrates and real
samples [124]. Chan et al. [125] developed a microbial sensor for rapid measurement of the amount of
biodegradable substances based on the salt-tolerant yeast A. adeninivorans LS3. They immobilized
 
 
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