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Bacteria electrode

Tissue and Bacteria Electrodes The limited stability of isolated enzymes, and the fact that some enzymes are expensive or even unavailable in the pure state, has prompted the use of cellular materials (plant tissues, bacterial cells, etc.) as a source for enzymatic activity (35). For example, banana tissue (which is rich with polyphenol oxidase) can be incorporated by mixing within the carbon paste... [Pg.182]

Background current, 21, 65 Background subtraction, 40, 106 Bacteria electrode, 182 Band microelectrodes, 130, 135 Beryllium, 82 Bienzyme electrodes, 175 Biocatalytic devices, 172 Biological recognition, 171 Biosensors, 50, 171 Bipotentiostat, 106 Blood electrolyte, 165 Boltzmann equation, 19 Brain analysis, 40, 116 Butler-Volmer equation, 14... [Pg.205]

Oxidation-reduction potential Because of the interest in bacterial corrosion under anaerobic conditions, the oxidation-reduction situation in the soil was suggested as an indication of expected corrosion rates. The work of Starkey and Wight , McVey , and others led to the development and testing of the so-called redox probe. The probe with platinum electrodes and copper sulphate reference cells has been described as difficult to clean. Hence, results are difficult to reproduce. At the present time this procedure does not seem adapted to use in field tests. Of more importance is the fact that the data obtained by the redox method simply indicate anaerobic situations in the soil. Such data would be effective in predicting anaerobic corrosion by sulphate-reducing bacteria, but would fail to give any information regarding other types of corrosion. [Pg.387]

The most widely accepted criterion for protection of steel at room temperature (the protection potential) in aerobic conditions is - 0 - 85 V with respect to a Cu/CuSOa reference electrode. In anaerobic conditions -0-95 V (vs. Cu/CuSOa) is the preferred protection potential because of the possible presence of active sulphate-reducing bacteria (SRB). [Pg.120]

A simplification of the polarization resistance technique is the linear polarization technique in which it is assumed that the relationship between E and i is linear in a narrow range around E . Usually only two points ( , 0 are measured and B is assumed to have a constant value of about 20 mV. This approach is used in field tests and forms the basis of commercial corrosion rate monitors. Rp can also be determined as the dc limit of the electrochemical impedance. Mansfeld et al. used the linear polarization technique to determine Rp for mild steel sensors embedded in concrete exposed to a sewer environment for about 9 months. One sensor was periodically flushed with sewage in an attempt to remove the sulfuric acid produced by sulfur-oxidizing bacteria within a biofilm another sensor was used as a control. A data logging system collected Rp at 10-min intervals simultaneously for the two corrosion sensors and two pH electrodes placed at the concrete surface. Figure 2 shows the cumulative corrosion loss (Z INT) obtained by integration of the MRp time curves as ... [Pg.211]

Enzyme electrodes belong to the family of biosensors. These also include systems with tissue sections or immobilized microorganism suspensions playing an analogous role as immobilized enzyme layers in enzyme electrodes. While the stability of enzyme electrode systems is the most difficult problem connected with their practical application, this is still more true with the bacteria and tissue electrodes. [Pg.443]

Fig. 15.29 Comparison of bacteria deposited before (area a), within (area b) and after (area c) the ultrasound electrode area. Reprinted from Ref. 23 with permission. 2008 American Chemical Society... Fig. 15.29 Comparison of bacteria deposited before (area a), within (area b) and after (area c) the ultrasound electrode area. Reprinted from Ref. 23 with permission. 2008 American Chemical Society...
Bacterial electrodes [11, 31, 33, 46, 48, 49, 60] In this type of electrode, a suspension of suitable bacteria is placed between the sensor proper and a dialysis membrane that prevents passage of high-molecular substances (see fig. 8.3). The sensor is usually a gas probe. In the simple types of bacterial electrode, the determinand is converted by a suitable strain of bacteria into a product sensed by the gas probe. Thus it is possible to determine arginine [46], glutamine [48],/.-aspartic acid [31],/.-histidine [60] and nitrate [33]. Hybrid bacterial - enzyme electrodes contain both a bacterial strain and a suitable enzyme. For example, an extract from ivingas Neurospora chossa can be used as a source of NAD nucleosidase and an Escherichia coli culture as a source of nicotinamide deaminase, so that the electrode responds to NAD [49] as a result of the series of reactions... [Pg.204]

A potentiometric determination of lysozyme is based on a system similar to a bacterial electrode [11]. The cells of the bacteria, Mcrococcus lysodeicticus, readily accept trimethylphenyl ammonium ions (TMPA ) from the solution. Lysozyme decomposes the cell membranes and TMPA is liberated. The rate... [Pg.204]

The determination of the lysozyme activity using the bacterial electrode (see p. 139) can also be used for immuno-analysis of biotine and avidine. The determination is based on the inhibition reaction of avidine with the biotine-lysozyme conjugate. After the reaction, the conjugate is no longer capable of dissolving the cell wall of the bacteria. The determination of biotine is similar [15]. [Pg.205]

Most of the pro-oxidative enzymes of bacteria are stabilized inside the cell, but are very fragile outside the cell. Therefore, the view that analysis may be carried out via isolated enzymes for aromatic processing, perhaps coupled to an electrode of some kind, appears quite impractical. MCA takes advantage of what bacterial cells can actually do, namely to stabilize and protect enzymes, besides the initial synthesis. Hence, MCA is likely to be far more practical than any bioelectrode method for analysis. [Pg.545]

The bacteria consume oxygen during ammonia oxidation, so oxygen depletion can be detected by using an oxygen electrode. A combined creatinine sensor thus consists of a cellulose dialysis membrane, immobilized creatinine deaminase, immobilized nitrifying bacteria and an oxygen electrode [130]. [Pg.128]

Li and Bashir, 2002) with interdigitated electrodes for DEP capture of bacteria and the interdigitated measurement electrodes to monitor growth. Panel (B) is showing a conductance plot generated based on bacterial growth of arbitrary numbers of colony forming units (cfu)/ml. [Pg.26]

E the introduction of different ligands in the amine complexes increases E according to the order I < CN < SCN < Br < Cl < NO2 [159, 160]. Finally, we mention the famous cisplatin, cis-Pt(NH3)Cl2, which is a very powerful cancer chemotherapy drug [161]. Its effect was discovered by Rosenberg [162] accidentally when he investigated the influence of electric field on living cells. He used supposedly inert platinum electrodes to study the suspension of live Escherichia coli bacteria. It was found that, as a consequence of dissolution of Pt, cisplatin was formed which had a devastating effect on the bacteria. [Pg.516]

Hikuma M, KuboT, Yasuda T, Karube I, Suzuki S (1980) Ammonia electrode with immobilized nitrifying bacteria. Anal Chem 52 1020 -1024... [Pg.116]

The mitochondrial membrane potential Em (or Ay) is the potential difference measured across a membrane relative to a reference electrode present in the surrounding solution.176 For both mitochondria and bacteria Em normally has a negative value. The Gibbs energy change AyH+ for transfer of one mole of H+ from the inside of the mitochondrion to the outside, against... [Pg.1038]

Chemolithotrophic organisms often grow slowly, making study of their metabolism difficult.310 Nevertheless, these bacteria usually use electron transport chains similar to those of mitochondria. ATP is formed by oxidative phosphorylation, the amount formed per electron pair depending upon the number of proton-pumping sites in the chain. This, in turn, depends upon the electrode potentials of the reactions involved. For example, H2, when oxidized by 02, leads to passage of electrons through the entire electron transport chain with synthesis of 3 molecules of ATP per electron pair. On the other hand, oxidation by 02 of nitrite, for which E° (pH 7) = +0.42 V, can make use only of the site III part of the chain. Not only is the yield of ATP less than in the oxidation of H2 but also there is another problem. Whereas reduced pyridine... [Pg.1050]

V). The centers resemble PSII of chloroplasts and have a high midpoint electrode potential E° of 0.46 V. The initial electron acceptor is the Mg2+-free bacteriopheophytin (see Fig. 23-20) whose midpoint potential is -0.7 V. Electrons flow from reduced bacteriopheophytin to menaquinone or ubiquinone or both via a cytochrome bct complex, similar to that of mitochondria, then back to the reaction center P870. This is primarily a cyclic process coupled to ATP synthesis. Needed reducing equivalents can be formed by ATP-driven reverse electron transport involving electrons removed from succinate. Similarly, the purple sulfur bacteria can use electrons from H2S. [Pg.1301]


See other pages where Bacteria electrode is mentioned: [Pg.213]    [Pg.213]    [Pg.1180]    [Pg.1180]    [Pg.1377]    [Pg.209]    [Pg.226]    [Pg.240]    [Pg.10]    [Pg.384]    [Pg.134]    [Pg.347]    [Pg.144]    [Pg.272]    [Pg.110]    [Pg.1103]    [Pg.174]    [Pg.172]    [Pg.372]    [Pg.118]    [Pg.130]    [Pg.28]    [Pg.29]    [Pg.553]    [Pg.169]    [Pg.981]   
See also in sourсe #XX -- [ Pg.215 ]

See also in sourсe #XX -- [ Pg.182 ]




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Tissue and Bacteria Electrodes

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