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ABSTRACT: The rates of the mineralization processes initiated by the input of plant residues and pyrogenically modified plant material
into gray forest soil under forests and meadows were assayed. While meadow plant residues was mineralized more rapidly than
the forest floor, decomposition of the pyrogenic material resulted in disproportional changes in CO2 emission from soils. Statistical treatment showed that the respiratory activity of CO2 emission by heterotrophic microorganisms, which is a physiological characteristic of microbial communities, is 89% determined
by the substrate quality. The maximal specific growth rate, which reflects the functional changes in microbial communities,
was affected by the cenosis (36%) and the substrate (30%). Most of the carbon of the original plant material (up to 90%) was
removed during the burning of plant substrates. The remaining compounds in the pyrogenically transformed material changed
the process of mineralization in soil compared both to the control variant and to soil enriched with plant residues. Input
of plant residues and ash into the soil resulted in increased total and active biomass, while the maximal specific growth
rate decreased and the generation time for the active biomass increased. In the case of soils with plant residues, these changes
in the state of microbial communities were brief and occurred during the period of intense mineralization (0–5 days), while,
in soils with plant ash, stable changes were revealed after more prolonged incubation. Experimental determination of the microbial
biomass turnover time (MTT) by means of two methods (from the ratio between the microbial biomass and respiration and from
microbial specific growth rates) made it possible to determine the economical coefficient Y for microbial communities metabolizing
the substrates of different availability. Depending on the experimental variant, the Y values varied from 0.22 to 0.51. Decreased
maximal specific growth rate and increased values of Y (the coefficient of efficiency of substrate utilization) showed the
predominant contribution of K-strategists in the mineralization of low available substrates in soil. The balance calculations
and physiological characteristics of the microbial community suggested that the priming effect was most probable in soils
enriched with plant ash.
KeywordsCO2 emission–microbial growth kinetics–mineralization of organic matter–microbial biomass
Microbiology 05/2012; 80(2):194-204. · 3.06 Impact Factor
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ABSTRACT: The effects of lead oxide and lead nitrate on the growth strategies of microbial communities in the soil and in the rhizosphere
of orchard grass (Dactylis glomerata L.) were studied. The maximum specific growth rate of the microorganisms (μm) changed significantly when the concentration of mobile forms of lead in the soil exceeded 170 mg Pb/kg, which corresponded
to the addition of 400–1000 mg Pb/kg of soil in the form of lead nitrate. The addition of lead resulted in the suppression
of a part of the r-strategists and in the more active development of the K-strategists in the adapted microbial community. It was demonstrated that the community of rhizosphere microorganisms could
be a more sensitive indicator of lead pollution than the nonrhizosphere microbial community. The values of the auxotrophy
index (the ratio between the μm values upon the growth on glucose and yeast extract) demonstrated a tendency towards a decrease in the metabolic diversity
of the soil microbial community under the impact of lead.
Eurasian Soil Science 05/2006; 39(6):653-660. · 0.25 Impact Factor
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ABSTRACT: The effects of lead oxide and lead nitrate on soil microorganisms were studied in a field experiment. As soon as the soil
was treated with lead, a response of the microbial community was expressed in the higher rate of the basal respiration irrespectively
of the dose and form of the lead compounds applied. At the same time, the microbial biomass decreased in the variants contaminated
with 100–1000 mg Pb/kg. The long-lasting influence of lead lowered the basal respiration and the microbial biomass in the
variant with the application of 400–1000 mg Pb/kg in the form of nitrate and 1000 mg Pb/kg as oxide. The experiments proved
that the content of mobile lead in the soil, irrespectively of the form and solubility of the lead compounds, controls the
functional relationship between the effect of the lead and the microbiological indices of the soil. The suppression of the
soil microbial activity by more than 25% took place when the mobile lead content exceeded 170 mg Pb/kg.
Eurasian Soil Science 04/2006; 39(5):498-506. · 0.25 Impact Factor
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ABSTRACT: Dominant growth strategies of soil microbial communities of mown and unmown meadows were assessed with respect to the constants of saturation and maximal specific growth rate of microorganisms. The microbial community of mown-meadow soil was characterized by a greater biomass and activity due to prevalence of microorganisms with the r strategy, compared to the microbial community of unmown-meadow soil. In contrast to nonrhizosphere soil, rhizosphere soil was dominated by rapidly growing microorganisms with the r strategy. The dependence of the dominant ecological strategy of the rhizosphere microbial community on the vegetation stage of plants has been traced. Study of the effect of plant species on the growth strategies of rhizosphere microorganisms showed that the features of the K strategy are more pronounced in the following rhizosphere microbial communities of grasses at the same growth stage: r strategy–Bromopsis inermis L.–Poa pratensis L., P. compressa L.–Dactylis glomerata L.–Festuca pratensisL.–K strategy. In the absence of limitation by climatic factors, the growth strategies of rhizosphere microorganisms are determined by the competition between microorganisms and plants for nutrients.
Biology Bulletin 10/2004; 31(6):620-627. · 0.20 Impact Factor
