[Determination of nitrogen fixation activity by an acetylene method for setting the hygienic standard for the soil content of heavy metals].
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Acetylene↗
Biomedical subjects
D G Zviagintsev
Publications and source records attributed to D G Zviagintsev.
[Adsorption of bacteria on glass, modified glass surfaces and polymer films].
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Adsorption↗
[Adsorption of bacteria on glass and silicone].
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Adsorption↗
[Population dynamics of oligosporous actinomycetes in Chernozem soil].
Investigation of the dynamics of an oligosporous actinomycete population in chernozem soil in the course of succession induced by soil wetting allowed us to reveal the time intervals and conditions optimal for the isolation of particular oligosporous actinomycetes. Saccharopolysporas and microbisporas proved to be best isolated in the early and late stages of succession, whereas actinomycetes of the subgroup Actinomadura and saccharomonosporas could be best isolated in the early and intermediate stages of succession.
Actinomycetales↗
[Reproductive resting forms of Arthrobacter globiformis].
Submerged cultures of Arthrobacter globiformis grown in media unbalanced with respect to carbon and nitrogen sources were found to contain cells exhibiting features typical of resting forms: long-term viability, specific ultrastructure, dormant metabolism, and thermoresistance. Such cells were produced not only in the collection strain VKM B-1112, but also in the A. globiformis strains isolated from 2- to 3-million-year-old permafrost sediments.
Adaptation, Physiological↗
[Effect of phosphorus on the colonization of barley rhizosphere by microorganisms].
The mineral phosphorus supply produced two outbreaks in the bacterial population of the barley rhizosphere and rhizoplane but inhibited the growth of fungal mycelium. The inhibition of mycelial growth might be due to the exudation of specific inhibitors by barley roots, since the most pronounced inhibition was observed at high doses of supplementary phosphorus.
Bacteria↗
[Structure and function of microbial communities in soil from the southern Taiga].
General regularities in the structure of the microbial communities of southern taiga soil ecosystems and taxonomic differences between the microbial communities of soils with different hydrothermal characteristics are discussed with reference to the main types of soils of the Central State Forest Biosphere Reserve.
Bacteria↗
[Microsampling of rhizosphere soil and laboratory artefacts].
A parallel analysis of the microsamples of surrounding soil and microsamples of rhizosphere soil did not reveal the so-called rhizospheric effect. The data obtained showed that dilution significantly influences the results of determination of the number of soil microorganisms. The actual number of microorganisms revealed in soil samples greatly differed from the theoretically predicted values. The enumeration of microorganisms in soil microsamples by direct count and, especially, by the plating method with the use of conversion coefficients based on the degree of sample dilution gave erroneous results.
Artifacts↗
[Regulation of the biomass and activity of soil microorganisms by microfauna].
Microcosm experiments showed that the microbial biomass and the respiration activity in soil were regulated by nematodes. Depending on nematode number and plant residue composition, the trophic activity of nematodes can either stimulate or inhibit microbial growth and respiration as compared to soil containing no nematodes. The stimulating effect was observed when nitrogen-free (starch) or low-nitrogen (wheat straw, C:N = 87) organic substrates were applied. Inhibition occurred when a substrate rich in nitrogen (alfalfa meal, C:N = 28) was decomposed and the nematode population exceeded the naturally occurring level. A conceptual model was developed to describe trophic regulation by microfauna (nematodes) of the microbial productivity and respiration activity and decomposition of not readily decomposable organic matter in soil. The stimulating and inhibiting influence of microfauna on soil microorganisms was not a linear function of the rate of microbial consumption by nematodes. These effects are largely associated with the induced change in the physiological state of microorganisms rather than with the mobilization of biogenic elements from the decomposed microbial biomass.
Animals↗
[Bacterial soil variety: evaluation of methods, possibilities, and prospects ].
The paper presents a comparative description of the modern molecular genetic and routine culture techniques for assessing microbial diversity in soils and gives analysis for the different results obtained by these two groups of methods. The necessity of the collaboration of soil scientists, microbiologists, and molecular biologists in integrating different research methods for a proper assessment of soil microbial diversity is discussed. The paramount importance of soil as the source and reserve of biodiversity on the Earth is emphasized.
Bacteria↗
[Structure of bacterial complexes of the river Protva flood-plains].
The synecological analysis of bacterial communities from the Protva River flood-plain biogeocenosis showed that all of the horizons contain spirilla, which are typical hydrobionts, and pigmented coryneform bacteria associated with the herbaceous plants of the flood-plain meadows. The alluvial meadow soils of the inundated regions of the floodplain differed from the unflooded regions of the flood-plain in that they had a more diverse bacterial population continuously distributed over the soil profile.
Bacteria↗
[Bacterial diversity in microcosms of soils with various humidity].
The succession analysis of bacterial diversity in the A horizons (rich in organic matter) of three contrasting types of soil--burozem, soddy gley soil, and chernozem--showed that the bacterial diversity of soil microcosms in humid regions can be adequately evaluated only if soil samples are incubated at different soil moisture contents. A complete account of actinobacteria and proteobacteria requires the levels of soil moisture corresponding to the maximum capillary-sorption moisture and capillary moisture, respectively. The bacterial diversity, whose value was maximum on the 40th day of succession, was higher in soddy gley soil than in burozem. The taxonomic structures of the bacterial communities of these two types of soil were different. After wetting chernozem samples from arid regions, the soil bacterial community changed insignificantly with time and drastically differed from that of soils from humid regions. The difference in the bacterial diversity of soils was the most distinct when it was evaluated by measuring the proportion between proteobacteria and actino-bacteria.
Bacteria↗
[All-Russian Scientific Conference "Prospects of Development of Soil Biology" (on 100th birthday of Academician E N Mishustin)].
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Biology↗
[The growth-promoting effect of Beijerinckia and Clostridium sp. cultures on some agricultural crops].
New strains of Beijerinckia mobilis and Clostridium sp. isolated from the pea rhizosphere were studied with respect to their promoting effect on the growth and development of some agricultural crops. Seed soaking in bacterial suspensions followed by the soil application of the suspensions or their application by means of foliar spraying was found to be the most efficient method of bacterization. The application of B. mobilis and Clostridium sp. cultures in combination with mineral fertilizers increased the crop production by 1.5-2.5 times. The study of the population dynamics of B. mobilis by the method of genetic marking showed that this bacterium quickly colonized the rhizoplane of plants and, therefore, had characteristics of an r-strategist. At the same time, Clostridium sp. was closer to K-strategists, since this bacterium slowly colonized the econiches studied. The introduction of the bacteria into soil did not affect the indigenous soil bacterial complex. The presence of Clostridium sp. slowed down the colonization of roots by the fungal mycelium. The possible mechanisms of the plant growth-promoting activity of B. mobilis and Clostridium sp. are discussed.
Azotobacter↗
[Tolerance of soil bacterial complexes to salt shock].
Investigations showed that bacteria present in soil are resistant to one-day exposure to a saturated solution of ammonium nitrate and can well develop when transferred to laboratory nutrient media. The evaluated number of bacteria in NH4NO3-treated soil samples was nearly the same as in native soil samples, while was 1.5-2.5 times smaller in the former than in the latter case when microbial succession in the soil samples was initiated by wetting them. Bacteria (particularly gram-negative ones) occurring at the early stages of succession were the most sensitive to salt stress. Bacteria in soil were found to be much more resistant to salt stress than the same bacteria isolated in pure cultures.
Bacteria↗
[Acidophilic soil actinomycetes].
A clear-cut dependence of the distribution of acidophilic actinomycetes on the pH value of soil was established. Acidophilic actinomycetes were found to be present in soils whose pH does not exceed 6.8 (acid forest soils, lowland peaty soil, and ordinary chernozem) and not in slightly alkaline soils (chestnut sodic and alluvial meadow soils). In the acid lowland peaty soil, the species diversity of acidophilic streptomycetes was lesser than the species diversity of streptomycetes revealed in the same soil by using neutral medium.
Actinomycetales↗
[Actinomycetes in the rhizosphere of barley plants grown in the strongly acidic soddy podzolic soil].
The study of various factors (soil acidity, the variety of barley plants, and their developmental phases) on the rhizosphere actinomycete complex showed that it is soil acidity that substantially influences the population of rhizosphere actinomycetes. The effect of soil acidity was most likely due to the different tolerance of rhizosphere actinomycetes to high concentrations of the aluminum and hydrogen ions. The developmental phases of barley plants correlated with the population indices of only one genus of actinomycetes, Micromonospora.
Acids↗
[Actinomycetes of the genus Micromonospora in meadow ecosystems].
Investigations showed that micromonosporas, along with streptomycetes, are the major inhabitants of floodplain meadow ecosystems, where their population varies from tens of thousands to hundreds of thousands of CFU per g substrate. In spring, the population of micromonosporas in soil and on the plant roots was found to be denser than that of streptomycetes.
Actinomycetales↗