[Bacterial motion in porous media]. / Dvizhenie bakterii v poristykh sredakh.

The motion of chemotactically different Escherichia coli C600, cheB287, and AW405 cells was studied using a column packed with silica gel. The model chemotaxis of bacteria in porous media seems to be adequate to natural bacterial chemotaxis in soils. The porous structure of silica gel prevents interfering convective flows. Silica gel columns make it possible to separate bacterial cells differing in motility and chemotaxis. Relevant physical phenomena are discussed. The concept of fast and slow chemotaxis is considered.

[Bacterial chemotaxis to naphthalene]. / Izuchenie khemotaksisa bakterii k naftalinu.

The chemotaxis of two pseudomonads, P. putida AZ (Naph+) and P. putida AZ (Naph-), differing in the ability to metabolize naphthalene was studied by the known capillary method of Adler and the densitometric method devised in our laboratory. The migration of P. putida AZ (Naph+) cells toward increasing levels of naphthalene was accompanied by the formation of a migrating front of converted naphthalene. P. putida AZ (Naph-) cells, too, exhibited positive chemotaxis to naphthalene, but they did not form the front of converted naphthalene. The analysis of experimental data in terms of a kinetic model of bacterial chemotaxis showed that the densitometric method is a potential tool for studying bacterial chemotaxis to hydrophobic organic substances.

[Kinetic analysis of behavior of chemotactic bacterial population at the interface of two media]. / Kineticheskii analiz povedeniia populiatsii khemotaksichnykh bakterii na granitse razdela dvukh sred.

The behavior of a population of bacteria at the boundary with a chemotactically active water medium containing the sites of specific binding to cell receptors was analyzed. A kinetic model of chemotaxis was used for the analysis. Differences in the behavior of strains metabolizing and not metabolizing the substrate were revealed. Six phases of interface taxis were distinguished and characterized. The results of the analysis were confirmed by the densitometric data.

[Kinetic analysis of the chemotaxis of bacteria]. / Kineticheskii analiz khemotaksisa bakterii.

On the basis of a kinetic model of bacterial chemotactic movement the system of differential equations was reduced to describe the phenomenon of bacterial bonds migration. It follows that Keller-Segel equation is a private case of a more general "diffusion approximation" of the kinetic model. The functional parameters of the reduced equation for E. coli K-12 are estimated.

[Reaction of endonuclease EcoRI with DNA of the plasmid ColEI]. / Reaktsiia vzaimodeistviia restriktazy EcoRI s DNK plazmidy ColEI.

Interaction of restrictase EcoRI with supercoiled and open forms of ColEI DNA is studied in the range 0-55 degrees. At temperatures 25-37 degrees superhelical ColEI DNA is converted to linear form, the most complete cleavage of supercoiled molecules were observed at 25 degrees. This reaction is not followed by accumulation of intermediate open circular DNA forms. At 45-55 degrees open circular DNA forms with nicks at the restriction site are formed along with linear molecules. Similar effects were observed at 10 degrees, whereas at 0 degree only open circular DNA molecules are formed.