[Effect of emissions from a copper-nickel plant on soil microbial communities in forest biogeocenoses of the Kola Peninsula].

The effect of industrial pollution with emissions from the Severonikel Copper-Nickel Plant (SCNP) on soil microbial communities of forest biogeocenoses has been studied taking into account their relative location under tree crowns (near the stem, in the undercrown area, or under gaps in the canopy). The results show that increasing technogenic pollution results in a significant decrease in the microbial biomass, basal respiration, and maximum specific growth rate, as well as in dominance of K-strategists in the microbial communities of polluted soils. The effect of location under the crown, compared to the intercrown area, manifests itself in dominance of rapidly growing microorganisms with the r-strategy. However, emissions from the SCNP inhibit the growth of r-strategists, and the location-dependent differences between microbial communities are leveled off in areas with the highest pollution level.

[Microbial biomass and growth kinetics of microorganisms in chernozem soils under different farm land use modes].

The carbon content of microbial biomass and the kinetic characteristics of microbial respiration response to substrate introduction have been estimated for chernozem soils of different farm lands: arable lands used for 10, 46, and 76 years, mowed fallow land, non-mowed fallow land, and woodland. Microbial biomass and the content of microbial carbon in humus (Cmic/Corg) decreased in the following order: soils under forest cenoses-mowed fallow land-10-year arable land-46- and 75-year arable land. The amount of microbial carbon in the long-plowed horizon was 40% of its content in the upper horizon of non-mowed fallow land. Arable soils were characterized by a lower metabolic diversity of microbial community and by the highest portion of microorganisms able to grow directly on glucose introduced into soil. The effects of different scenarios of carbon sequestration in soil on the reserves and activity of microbial biomass are discussed.

[The antibiotic-aided separation of fungal and bacterial substrate-induced respiration in various soil ecosystems].

Fungal and bacterial substrate-induced respiratory activities have been distinguished in gray forest and chestnut soils in various ecosystems (forest, grassland, tillage, unused land, and shelterbelt) using the antibiotics cycloheximide and streptomycin. The optimal inhibitory concentrations of the antibiotics, added separately and in combination; the preincubation time of the antibiotics with the soil before glucose addition; and the mass of added inert material (talc) have been determined. Based on the results obtained, the inhibitor additivity ratio (IAR) has been calculated for the antibiotics. With the IAR differing from 1.0 by a value of more than 5%, the fungal and bacterial substrate-induced respiratory activities can not be distinguished reliably. Respiration measurements show that the microbial communities of natural ecosystems are dominated by fungi (81-95% on average). The smallest amount of fungi (54-59%) is found in the tillage ecosystem.

[Ecological strategies of soil microbial communities under plants of meadow ecosystems]. / ékologicheskie strategii microbnykh soobshchestv pochv pod rasteniiami lugovykh ékosistem.

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 rhizosphere microbial community on vegetation stage of plants has been traced. The effect of plant species on the growth strategies of rhizosphere microorganisms was studied. It was found that the features of the K strategy are manifested more strongly in the series of rhizosphere microbial communities of grasses at the same stage of development: r strategy--Bromopsis inermis L.--Poa pratensis L., P. compressa L.--Dactylis glomerata L.--Festuca pratensis L.--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 substrate.

[Quantitative isolation of microbial DNA from the different types of soils of natural and agricultural ecosystems]. / Kolichestvennaia ékstraktsiia mikrobnoi DNK iz raznykh tipov pocv prirodnykh i agrotsenozov.

A novel procedure was developed for direct quantitative isolation of microbial DNA from soil. This technique was used to evaluate microbial DNA pools in soils of contrasting types (chernozems and brown forest soils) under different anthropogenic loads. A strong correlation was found between microbial biomass and DNA contents in soils of different types (R2 = 0.799). The ratio of soil CO2 emission rate to the amount of extractable DNA in the soil was shown to reflect physiological state of the soil microbial community; this ratio can be used as an ecophysiological parameter similarly to the metabolic quotient qCO2.

[Extractable microbial DNA pool and microbial activity in paleosols of Southern Ural]. / Pul ékstragiruemoi mikrobnoi DNK i mikrobiologicheskaia aktivnost' paleopochv Iuzhnogo Priural'ia.

An evaluation of microbial DNA pools was performed using direct quantitative isolation of DNA from contemporary soils of Southern Urals and paleosols sealed under burial mounds of early Bronze Age more than 5000 years B.P. Significant regression dependence was found between the biomass and DNA contents in these soils (R2 = 0.97). Activity and dominant ecological strategies of microbial communities of paleosols and contemporary southern black soil were compared from growth parameters obtained by analysis of respiratory curves. The ratio of maximum specific growth rates of soil microorganisms on glucose and on yeast extract was shown to provide an auxotrophy index for soil microbial communities.