[Evaluation of substrate specificity of biosensor models based on strains degrading polycyclic aromatic compounds].

Models of microbial biosensors based on 11 strains of degrading surface-active substances (SASs) and polycyclic aromatic hydrocarbons (PAHs) were studied. Substrate specificity, sensitivity, and stability of biosensor models were comparatively evaluated.

[Biosensor of the reactor type based on Rhodococcus erythropolis HL TM-1 cells for determining 2,4-dinitrophenol]. / Biosensor reaktornogo gipa na osnove kletok Rhodococcus erythropolis HL PM-1 dlia opredeleniia 2,4-dinitrofenola.

A model of a reactor-type biosensor based on the Rhodococcus erythropolis HL PM-1 was developed for amperometric detection of 2,4-dinitrophenol (2,4-DNP). The effects of the matrix material (agar and calcium alginate gels, ceramic support, and cellulose powder) on the biosensor signal concentration dependence, detection time, and biosensor stability were studied. In case of bacterial cells immobilized on cellulose powder, the lower limit of 2,4-DNP detection was 20 microM and the time of single analysis, the biosensor recovery included, was 30-50 min. In the continuous detection mode, the biosensor response was maintained at a stable level without biosensor inactivation for ten days. The biosensor can be used as an element of a complex analytical system for detecting nitroaromatic compounds in samples.

[Development of biosensors for phenol determination from bacteria found in petroleum fields of West Siberia]. / Bakterii iz pochv mestorozhdenii Zapadnoi Sibiri kak osnova biosensorov dlia opredeleniia fenola.

Nine Gram-negative bacterial strains, selected from 300 strains isolated from soils of the West Siberian petroliferous basin and growing on oil and oil products, consume phenol as a single carbon and energy source. The strains were used for the development of a sensor bioreceptor. The most active 32-I strain was shown to bear a plasmid responsible for phenol degradation. The plasmid-free derivative of this strain, 32-I-1, did not grow on phenol. The possibility of creating a model biosensor for phenol based on the plasmid-containing 32-I strain is considered. The detection limit for phenol was 5 microM. The optimum conditions for the sensor operation are: pH 7.4, 35 degrees C, and operation time 30 h.

[Effect of conditions of culturing Pseudomonas rathonis T on characteristics of a biosensor for determining anionic surface-active agents]. / Vliianie uslovii kul'tivirovaniia Pseudomonas rathonis T na kharakteristiki biosensora dlia opredeleniia anionnykh poverkhnostno-aktivnostno-aktivnykh veshchestv.

The dependence of the sensitivity of a microbial biosensor of anionic surfactants (AS) on the growth phase of Pseudomonas rathonis T, a strain capable of degrading surfactants, was studied. Correlations were found between the optimum values of temperature and pH of microbial growth, substrate utilization, and functional performance of the microbial biosensor. These results allow the process of AS detection to be optimized.

[Effect of various methods of immobilization on stability of a microbial biosensor based on Pseudomonas rathonis T during detection of surfactants]. / Vliianie razlichnykh sposobov immobilizatsii na stabil'nost' mikrobnogo biosensora na osnove Pseudomonas rathonis T pri detektsii poverkhnostno-aktivnykh veshchestv.

The operating and storage stability of a receptor element of an amperometric biosensor based on the Pseudomonas rathonis strain T capable of degrading surfactants was tested. Microbial cells were immobilized by incorporation in gels (agar, agarose, and calcium-alginate), polyvinyl alcohol membrane, adhesion to the chromatographic paper GF/A, or by the cross-linking induced by glutaric aldehyde. Incorporation of microbial cells in agar gel provides the long-standing conservation of their activity and viability during measurements of high concentrations of surfactants and allows the receptory element of the biosensor to be rapidly recovered after the measurements.

[Sensor for rapid measurement of blood glucose]. / Sensor dlia ékspress-otsenki kontsentratsii gliukozy v syvorotke krovi.

Bacterial biosensor consisting of Gluconobacter oxydans cells immobilized on the surface of oxygen electrode was used for measuring glucose concentration in human blood serum. The results were compared with those of standard clinical method (color reaction with ortho-toluidine). The proposed biosensor permits highly accurate measurements (mean quadratic deviation no more than 2% of the mean arithmetic), the coefficient of correlation with the results of standard method being 0.970.