[Mathematical modeling of the spatial distribution of the pollen produced by genetically modified crops].

We represent and analyze the results of mathematical simulation of pollen dispersion from the origin, a field sowed by genetically modified plants. Factors responsible for the genetic isolation of such fields are discussed.

[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.

Chemotaxis in polycyclic aromatic hydrocarbon-degrading bacteria isolated from coal-tar- and oil-polluted rhizospheres.

Abstract The limited mass transfer in polycyclic aromatic hydrocarbon (PAH)-contaminated soils during bioremediation treatments often impedes the achievement of regulatory decontamination end-points. Little is known about bioavailability of these hydrophobic pollutants in phytoremediation systems. This work attempts to evaluate, for the first time, chemotaxis as a bioavailability-promoting trait in PAH-degrading bacteria from the rhizosphere. For this aim, 20 motile strains capable of degrading different PAHs were isolated from rhizosphere soils contaminated with coal tar and oil. Three representative Pseudomonas strains were selected, on the basis of their faster growth and/or range of PAHs degraded, for detailed chemotaxis studies with PAHs (naphthalene, phenanthrene, anthracene, and pyrene), bacterial lipopolysaccharide and root exudates from seven different plants. The chemotactic response was quantified with a new densitometric method. The results indicate that chemotaxis is a relevant mobilizing factor for PAH-degrading rhizosphere bacteria.

[The sensitivity of Pseudomonas mallei strains to antibacterial preparations in in-vitro experiments on a cell culture model]. / Izuchenie chuvstvitel'nosti shtammov Pseudomonas mallei k antibakterial'nym preparatam v opytakh in vitro na modeli kletochnykh kul'tur.

The cytopathogenic action of P. mallei on macrophages of golden hamsters and transplantable Hep-2 cell culture was studied. It was shown that the culture test systems may be efficient in estimation of the P. mallei virulent properties. The effect of antibacterial drugs on intracellular P. mallei was also studied.

[Nitrogen fixation in combined cultures of Lipomyces and bacteria]. / Azotfiksatsiia v sovmestnykh kul'turakh Lipomyces s bakteriiami.

Nitrogen fixation by pure cultures of soil yeasts belonging to the genus Lipomyces Lodder et Kreger van Rij was not found by the acetylene method on a medium containing microelements and yeast autolysate. In a binary culture of L. lipofer 133 and Pseudomonas sp. 5, a nitrogen fixing bacterium, the content of bound nitrogen was 3.6 times higher in aerobic conditions and 15 times higher in anaerobic conditions than its accumulation by individual bacterial culture.