[Cultivation of Pseudomonas aeruginosa dissociants under specified limitation conditions].

The possibility of controlling the development of microbial communities was investigated on the basis of experimentally determined requirements for basic nutrients in R, S, and M dissociants of Pseudomonas aeruginosa. On media with the limitation conditions preset on the basis of the predictions of a mathematical model, exhaustion of glucose was experimentally confirmed for all monocultures and mixed cultures, as well as balanced consumption of glucose, nitrogen, and phosphorus by the R dissociant at the corresponding initial medium composition. The experimentally determined composition of mixed cultures was found to conform to the ones calculated using the mathematical model. The data obtained suggest the possibility of cyclic consumption of phosphorus by P. aeruginosa.

[Quantitative patterns of development of community of Pseudomonas aeruginosa dissociants].

The stationary phase of batch culture of Pseudomonas aeruginosa dissociants has been described by a variational model of consumption and growth. The generalized entropy functional was used as the objective function. The model parameters include the requirements of the dissociants for the main nutrients: carbon, nitrogen, and phosphorus. The variational model was used to calculate the limiting regions and microbial community composition during stationary growth for different initial combinations of the resources as a function of the limiting resources. A correspondence between the experimental data and model calculations has been demonstrated. A possibility to control the community structure is discussed.

[On the regulation of the ecological community structure by a variation of the concentration ratios of resources in environment]. / O regulirovanii sostava ékologicheskogo soobshchestva s pomoshch'iu izmenenuia otnosheniia kontsentratsii resursov v srede.

The possibility to regulate the structure of a community using a variational model of the ecological community was studied. The dependences of relative numbers of microorganisms on the initial ratios of resources of nutrients in environment were obtained. The potential possibility of controlling the community structure was shown. Model calculations and experimental data obtained on a community of Chlorococcales indicated that, as the ratios of resources vary, a change of the dominating species takes place.

[The requirements of Pseudomonas aeruginosa dissociants for carbon, nitrogen, and phosphorus]. / Opredelenie potrebnosti dissotsiantov Pseudomonas aeruginosa v uglerode, azote i fosfore.

Quantitative data on the nutritional requirements of microorganisms are necessary to predict the behavior of bacterial populations and to control their cultivation. The requirements of the R, S, and M dissociants of Pseudomonas aeruginosa for carbon, nitrogen, and phosphorus were derived from the results of 88 cultivation experiments. For each of the dissociants, we derived a coefficient that relates the optical density and the number of cells in the dissociant culture, determined the time when the cultures entered the stationary growth phase, studied cultural changes induced by transfer to the stationary phase, and determined what nutrients limit the growth of particular dissociants. The nutritional requirements of the dissociants are discussed in relation to our earlier data.

[Population size and areas of stratification in the variational model of ecosystem]. / Vidovye obiliia i oblasti limitirovaniia v variatsionnoi modeli ékologicheskogo soobshchestva.

The formulations of the variational task for finding the relative population size of species in community at a stationary stage of growth and of the theorem of stratification are given. Algorithms of finding the relative size of populations for communities consisting of two and three species consuming two or three resources were obtained. The borders of areas of stratification were described in which one, two, or three resources are limiting. For two species and two resources, the formulae of the dependence of relative size on the ratio of resources were derived, and the shape of this dependence for real requirements of species was demonstrated.

[Requirements for glucose, nitrate and phosphate and their variants in the analysis of the mixed culture of Pseudomonas aeruginosa variants]. / Potrebnosti v gliukoze, nitratakh, fosfatakh i ikh variatsii v analize smeshannoi kul'tury dissotsiantov Pseudomonas aeruginosa.

The calibration data and sensitivity analysis for the variational model of Pseudomonas aeruginosa mixed culture containing R, S, and M phenotypic variants are presented. The model with calibrated parameters (requirements of the variants for glucose, nitrates, and phosphates) adequately describes the experiment. The sensitivity indices (the species abundances and total community size) changed least under the influence of the parameter variations in the one-way limitation areas. The variant proportions are more sensitive to variation of the requirements than the community size.