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N S Pechurkin

Publications and source records attributed to N S Pechurkin.

At least 37 records · Page 2Linked to original sources
PubMed2000

Methodology of biospherics for theoretical sciences and practical use.

This article deals with some methodological aspects of biospherics connected with theoretical sciences development and prospective use for practical application. Properties of experimental objects, methods and goals of biospherics as synthesising science have been discussed. The problem of stability of incomplete (natural and artificial) ecosystems has been considered. The concept of the ecosystem health based on effective functioning of different types of ecosystems has been developed.

Biomass↗
PubMed1999

Modelling of genetically engineered microorganisms introduction in closed artificial microcosms.

The possibility of introducing genetically engineered microorganisms (GEM) into simple biotic cycles of laboratory water microcosms was investigated. The survival of the recombinant strain Escherichia coli Z905 (Apr, Lux+) in microcosms depends on the type of model ecosystems. During the absence of algae blooming in the model ecosystem, the part of plasmid-containing cells E. coli decreased fast, and the structure of the plasmid was also modified. In conditions of algae blooming (Ankistrodesmus sp.) an almost total maintenance of plasmid-containing cells was observed in E. coli population. A mathematics model of GEM's behavior in water ecosystems with different level of complexity has been formulated. Mechanisms causing the difference in luminescent exhibition of different species are discussed, and attempts are made to forecast the GEM's behavior in water ecosystems.

Animals↗
PubMed1999

Key factors in development of man-made and natural ecosystems.

Key factors of ecosystem functioning are of the same nature for artificial and natural types. An hierarchical approach gives the opportunity for estimation of the quantitative behavior of both individual links and the system as a whole. At the organismic level we can use interactions of studied macroorganisms (man, animal, higher plant) with selected microorganisms as key indicating factors of the organisms immune status. The most informative factor for the population/community level is an age structure of populations and relationships of domination/elimination. The integrated key factors of the ecosystems level are productivity and rates of cycling of the limiting substances. The key factors approach is of great value for growth regulations and monitoring the state of any ecosystem, including the life support system (LSS)-type.

Ecological Systems, Closed↗
PubMed1999

A mathematical model of "plants-microorganisms" interaction on complete mineral medium and under nitrogen limitation.

A mathematical model concerning the interaction of plants and rhizospheric microorganisms on complete mineral medium and under nitrogen limitation has been constructed. The model takes into account the closeness of plants and microorganisms in terms of the matter released by the plant and consumed by the microorganisms. The effect of rhizospheric microorganisms on plant growth with normal carbon dioxide and complete mineral medium has been demonstrated. Plants interacting with microorganisms have a greater biomass than plants growing without microorganisms. Wheat growth stimulation by metabolites of rhizospheric microorganisms under laboratory conditions on artificial soil has been experimentally demonstrated (Pechurkin, 1997). Under nitrogen limitation, the biomass of plants, with or without microorganisms, is identical, and is substantially reduced as compared with the medium with standard nitrogen.

Biomass↗
PubMed1999

Experimental and mathematical models for small aqueous closed ecosystems with spatially separated components.

Experimental and theoretical models of closed "autotroph-heterotroph" (chlorella-yeast, chlorella-protozoa) ecosystems with spatially separated components have been created and studied. The chart of flows and interaction of components of gas-closed "chlorella-yeast" system have formed the basis describe mathematically the functioning of the given system, experimental results have been found to agree with computer solution of the problem in terms of quality. Investigation of the experimental model of the "producer-consumer" trophic chain demonstrated the role of protozoa in nitrogen turnover. "Production-decomposition" and "production-grazing-decomposition" cycle models has been theoretically analyzed and compared. The predator has been shown to be a more intensive mineralizer than the reducer component.

Animals↗
PubMed1999

Experimental models of small closed systems with spatially separated unicellular organism-based components.

Experimental models of small biotic cycles of different degree of closure and complexity with spatially separated components based on unicellular organisms have been studied. Gas closure of components looped into "autotroph-heterotroph" (chlorella-yeast) system doubled the lifetime of the system (as opposed to individually cultivated components). Higher complexity of the heterotroph component consisting of two yeast species also increased the lifetime of the system through more complete utilization of the substrate by competing yeast species. The lifetime of gas and substrate closed "producer-consumer" trophic chain (chlorella-paramecia) increased to 7 months. In 60 days the components' numbers reached their steady state followed by more than 40 cycles of the medium. The role of a predator organism (protozoan) in nitrogen cycling was demonstrated; reproduction of protozoa correlated directly with their emission of nitrogen in the ammonia form that is most optimum for growth of chlorella.

Animals↗
PubMed1999

Experimental microcosms as models of natural ecosystems for monitoring survival of genetically modified microorganism.

An experimental approach for investigation of genetically modified microorganisms (GMMO) introduced into model ecosystems to evaluate potential risk of propagation of recombinant plasmids in surrounding medium has been developed. The object of modeling was Escherichia coli Z905 strain with a recombinant plasmid with bacterial luminescence genes, which was introduced into water microcosms of different structure. The approach involves comprehensive investigation of GMMO at four hierarchical levels: molecular (retaining the structure of the plasmid and expression of cloned genes); cellular (variation of metabolic activity); population (competitive power and metabolic interactions of GMMO with indigenous microflora, migration of recombinant and natural plasmids); ecosystem (effect of GMMO and cloned genes on ecosystem parameters). The experimental evidence and theoretical estimates are intended to form grounds to develop a basic version of an ecological certificate for different GMMO variants.

Adaptation, Biological↗
PubMed1999

Small artificial ecosystems: response to variation of environmental factors (CO2 enrichment).

Response of "wheat plants--rhizospheric microorganisms--artificial soil"--a simple terrestrial ecosystem--to carbon dioxide increased in its atmosphere to 0.06% has been studied. It has been experimentally demonstrated that a simple ecosystem develops and functions different from its individual elements (components), in this case "plants-artificial soil" without microorganisms. With mineral nutrition unlimited and CO2 enrichment the system is capable of binding (involving into turnover) 40% more carbon than the system without microorganisms. With material balance as the basis, this article evaluates the contribution of a system's elements into its development, namely, the contribution of the photosynthesizing component and the contribution of microorganisms.

Biomass↗
PubMed1997

Plants--rhizospheric organisms interaction in a manmade system with and without biogenous element limitation.

The effect has been studied of inoculation of seeds of wheat with two species of rhizospheric microorganisms--Pseudomonas fluorescens and Pseudomonas putida--on young plant growth with complete and with nitrogen deficit mineral nutrition. With complete mineral medium, plants grown from seeds inoculated with bacteria of Pseudomonas genus (experiment plants) have been found to have better growth over plants not inoculated with these bacteria (control plants). The experiment plants had increased transpiration and their biomass had higher organic nitrogen content. With nitrogen deficit medium, the plants inoculated with bacteria and those without them, have not revealed changes in growth. Neither case demonstrated competition of microorganisms with plants for nitrogen sources.

Biomass↗
PubMed1985

[Effect of the agitation intensity and concentration of surface-active substances on the rate of oxygen sorption by a model sulfite-albumin medium].

The physicochemical properties of a model medium consisting of two substances, sodium sulfite and albumin, were studied. It was shown that the presence of a SAS in the sulfite solution significantly lowered the rate of oxygen sorption by the model medium. The higher the SAS concentration, the lower the sorption rate. When yeasts were grown on sulfite liquor under conditions of the reduced medium the rate of their growth and respiration did not significantly depend on aeration within wide ranges of its variation. The experiments with the model medium demonstrated that the aeration independence was due to indifference to oxygen not of the cells but of the medium as the result of its physicochemical properties. The effect of sorption hysteresis was also studied on the model medium. It was revealed that the rate of oxygen desorption from the medium was lower than that of oxygen sorption by the same medium. The effect was not observed when a nonionic SAS was added to the medium and the isoelectric point was almost reached. The effect was connected with impairment of oxygen diffusion through the medium surface film. Interaction of the substances included in the model medium was of physical nature.

Absorption↗