[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.

[Comamonas testosteroni strain TI as a potential base for a microbial sensor detecting surfactants]. / Shtamm Comamonas testosteroni TI kak potentsial'naia osnova kletochnogo sensora dlia obnaruzheniia poverkhnostno-aktivnykh veshchestv.

Strain Comamonas testosteroni TI, capable of degrading the nonionic surfactant (NIS) nonylphenolethoxylate (OP-10), was used for constructing a pilot cellular biosensor. The lower NIS detection limit for the biosensor was 0.25 mg/l. We studied the substrate specificity of the biosensor with respect to a wide range of organic compounds: surfactants, polyaromatic compounds (PAC), carbohydrates, alcohols, etc. It was shown that the biosensor based on Comamonas testosteroni TI did not respond to glucose, which was an advantage over the formerly described biosensor based on Pseudomonas rathonis T. The amplitude of the sensor response remained stable for 10 days.

[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.

[Genetic control of the destruction of surface-active agents]. / Geneticheskii kontrol' destruktsii poverkhnostno-aktivnykh veshchestv.

Degradation of anionic, cationic, and zwitterionic surfactants, such as alkylbenzene sulfonate, ethonium, amidobetaine, and alkylaminobispropionate, by pseudomonads can be controlled by plasmid genes. The majority of plasmids of surfactant-degrading strains are capable of conjugal transfer.

[Storage of Pseudomonas strains degrading the surfactants]. / Khranenie psevdomonad, razlagaiushchikh poverkhnostno-aktivnye veshchestva.

The survival rate and the destruction activity of Pseudomonas strains decomposing anionic and ampholytic surfactants were studied in the course of their storage for a long period of time. The strains were shown to remain viable and active after being freeze-dried for a year. Therefore, lyophilisation can be recommended as the main method of storage for bacterial strains decomposing the following surfactants: sulfoethoxylate, sulfonate, cyclimide, and amidobetaine.

[Genetic determination of degradation of ampholytic surfactants]. / Geneticheskaia determinatsiia razrusheniia amfolitnykh poverkhnostno-aktivnykh veshchestv.

Plasmid DNA was detected in Pseudomonas putida 141 and P. stutzeri AT strains which caused destruction of the ampholytic surfactants alkylamino-bis-propionate (AABP) and amidobetaine, respectively. As was demonstrated using genetic analytic procedures, the plasmids controlled AABP and amidobetaine destruction. No plasmid DNA was found in P. desmolytica C37 which caused cyclimide destruction or in Pseudomonas sp. 1 and Citrobacter freundii TO strains responsible for AABP destruction. Apparently, destruction of these xenobiotics was controlled by chromosomal genes.

[Purification and study of the properties of a desulfonating enzyme in Pseudomonas alcaligenes]. / Ochistka i izuchenie svoistv desul'foniruiushchego fermenta Pseudomonas alcaligenes.

An enzyme desulfonating anionic alkyl benzene sulfonate (ABS) surfactants was isolated from Pseudomonas alcaligenes TR and purified. The physicochemical and catalytic characteristics of the enzyme were studied. The kinetic constants of ABS desulfonation were determined and shown to depend on the length of a hydrocarbon radical. The molecular mass of the enzyme was found to be close to 60,000.

[Breakdown of alkyl sulfonate by Pseudomonas rathonis]. / Razrushenie alkilsul'fonata Pseudomonas rathonis.

Pseudomonas rathonis T/1 utilizing alkyl sulfonate, an anionic surfactant, as a sole source of carbon and energy was isolated from the soil taken near a plant producing synthetic detergents. Pseudomonas rathonis T, a more active variant of the above strain, was obtained by selection under the conditions of continuous cultivation. As was shown by identification of intermediate products in the destruction of alkyl sulfonate, its molecule is first cleaved at the C--S bond yielding higher aliphatic alcohols which are then oxidized to the corresponding carboxylic acids. The strain can be used for purification of industrial sewage containing anionic surfactants.