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1.
G. M. Zenova P. A. Kozhevin N. A. Manucharova M. S. Dubrova D. G. Zvyagintsev 《Biology Bulletin》2012,39(5):416-422
It has been demonstrated that complexes of mycelial bacteria (actinomycetes), in which the amount of psychrotolerant actinomycetes reaches hundreds of thousands of CFU/g of the soil (frequently exceeding the portion of mesophilic forms), are developed in peat and podzolic soils of the tundra and taiga at low temperatures. As actinomycetes grow and develop in cold soils, their mycelium increases in length. Use of the molecular in situ hybridization method (fluorescent in situ hybridization, FISH) demonstrated that the portion of metabolically active mycelial actinobacteria exceeds the portion of unicellular actinobacteria in the Actinobacteria phylum. Specific peculiarities of psychrotolerant populations in relation to the spectrum of consumed substrates (histidine, mannitol, saccharose) were established by the method of multirespirometric testing. 相似文献
2.
The structural and functional specificity of the chitinolytic microbial complex changes dramatically depending on the incubation
temperature of soil microcosms. It was shown that the highest rates of chitin degradation occurred in desert soils at high
temperatures (50°C); in the moderate and northern zones, these rates peaked at lower temperatures (5°C). The role of prokaryotes
as the main chitin degraders in soils incubated at high temperatures, with fungi more actively participating in chitin decomposition
at low temperatures, was shown for the first time. Fluorescent in situ hybridization (FISH) revealed the predominance of actinomycetes
in the metabolically active chitinolytic prokaryotic complex of desert soils (high temperatures); in the soils of the northern
latitudes (low temperatures), proteobacteria prevailed. The relationship between the taxonomic position of the dominant members
of the chitinolytic complex of soil microorganisms, isolated in pure cultures with the dominant phylogenetic groups and the
sequence types obtained by using molecular biological techniques (FISH) was revealed. 相似文献
3.
The biometric analysis of bacterial cells in soil by light, fluorescence, and scanning electron microscopy showed that their average size is 0.8 m in diameter, 1.4 m in length, and 0.7 m3 in volume. In soil loci with enhanced microbiological activity (the rhizoplane of plants and the intestinal tract of soil invertebrates), the average size of bacterial cells was found to be 40% smaller than that of cells occurring in other parts of soil. This is the first experimental evidence showing that the metabolic activity of soil bacteria, their concentration, and allometric parameters are related. 相似文献
4.
D. G. Zvyagintsev G. M. Zenova E. S. Lobakova G. M. Nikolaev E. O. Omarova E. A. Ivanova I. B. Savelyev 《Microbiology》2010,79(3):314-320
Associations of cyanobacteria and actinomycetes were formed experimentally from the cyanobacterium Anabaena variabilis ATCC 29413 and the streptomycetes isolated from apogeotropic roots of sago plants. Based on their phenotypic properties and
the 16S rRNA gene sequencing, the streptomycetes were identified as representatives of Streptomyces pluricolorescens (strains 1 and 2). Cyanobacteria developing in monoculture and in association with an actinomycete were essentially different
in their morphological and physiological-biochemical characteristics. In associations, cyanobacteria showed a higher (by tens
of times) nitrogen-fixing activity compared to the monoculture and the morphological modifications of which were not observed
in the monoculture (increase in cell size, increase in the portion of heterocysts among vegetative cells, appearance of the
forms of unbalanced growth of cyanobacteria as giant, disc-shaped, curved, and rhomboid cells). At extremely low humidity
(aw 0.50), associated cyanobacterial cells remained viable, whereas in the monoculture, chlorophyll decomposition and cells death
occurred. The methods of high-resolution (H1 600 MHz) nuclear magnetic resonance (NMR) and pulsed-gradient spin echo NMR revealed a fraction of mobile protons in lyophilized
samples of the cyanobacterium-actinomycete association, which was evidence of the presence of free water. This fraction was
not found in the lyophilized samples of cyanobacterial and streptomycete monocultures. The revealed differences can explain
the survival of cyanobacterial cells in associations. 相似文献
5.
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 andClostridium 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, Clostridiumsp. 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. mobilisand Clostridiumsp. are discussed. 相似文献
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T. I. Chernov A. D. Zhelezova N. A. Manucharova D. G. Zvyagintsev 《Biology Bulletin》2013,40(6):527-532
A comprehensive study of chitinolytic microbial complexes of the phylloplane from cultured and forest plants has been conducted. An increase of the number and biomass of metabolically active cells of the representatives of the domain Bacteria and a decrease in fungal biomass in the experimental microcosms have been shown to occur after the introduction of chitin. The characteristic features of the taxonomic structure of metabolically active chitinolytic complexes of the phylloplane of the plants studied have been elucidated. Representatives of the phyla Proteobacteria, Bacteroidetes, and Verrucomicrobia have been shown to play important roles in the chitinolytic complexes of green leaf samples, while mycelial actinobacteria of the phylum Actinobacyteria played a similar role in needles of coniferous trees. A collection of chitinolytic microorganism cultures isolated from the phylloplane of different plant species has been created. 相似文献
9.
N. N. Belcheva A. A. Istomina A. Yu. Zvyagintsev I. V. Epur A. A. Karpenko E. P. Karaulova 《Journal of Ichthyology》2017,57(6):913-918
In the laboratory experiment and in fish caught in conditionally clean and polluted areas, the presence of metabolites of polycyclic aromatic hydrocarbons in bile by methods of conventional and synchronous spectrofluorimetry was determined. The study showed that this approach is well suited for the detection of metabolites of polycyclic aromatic hydrocarbons with 2–3, 4, and 5–6 aromatic rings. If the content of metabolites of polycyclic aromatic hydrocarbons with 4 and 5–6 rings in bile is low, the method of synchronous spectrofluorimetry is less sensitive than conventional spectrofluorimetry. Both methods of monitoring are simple and fast and reflect the real picture of water pollution. 相似文献
10.
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 ctivity 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. 相似文献