[Estimation of abundance dynamics of gram-negative bacteria in soil].

Bacterial succession in soil was studied for two variants of initiation (moistening and moistening with addition of glucose). To determine the numbers of viable gram-negative bacteria, the modified nalidixic acid method was applied. The numbers of gram-negative bacteria revealed by this method were 2 to 3.5 times higher than those determined by the traditional method. In a developing community, the highest total bacterial numbers were observed on day 7; afterwards their numbers decreased and stabilized at a level exceeding four- to fivefold the initial one. In both experimental variants, the highest numbers of viable gram-negative bacteria were revealed on day 15 (75-85% of the total bacterial numbers). Morphology of these bacteria suggests their classification as cytophagas (chitinophagas) utilizing chitin from the dead fungal mycelium.

[Morphometric analysis of bacteria associated with soil Myriapoda].

Scanning electron microscopy revealed that the average cell size of bacteria associated with the digestive tract of soil Myriapoda was 0.65 microm in diameter, 1.36 microm in length, and 0.60 microm3 in volume. An example of Myriapoda illustrated that the intestinal tract bacteria of soil invertebrates shared the following features: (1) a high density level in this habitat; (2) existence mostly in the form of vegetative cells; (3) a cell size significantly smaller than that of bacteria functioning in soil; (4) a cell size closer to the lower limits of the size range characteristic for bacterial cultures grown in laboratory media. All this suggests that the bacterial community of the digestive tract differs from the typical soil community not only in composition, but also in a higher level of physiological activity.

[Properties of native and ortho- and pyrophosphate-modified Fe-humic complexes of the soil and their effect on solubility and toxicity of the products of exogenous Zn binding].

The properties of soil Fe-humic sorbent complexes proved to determine the level of exogenous Zn binding and the toxicity of Zn-compounds for soil microbiota. The properties of Fe-humic complexes were profoundly altered under the action of phosphate anions as potential ligands. Distinct properties of Fe-humic complexes modified by ortho- and pyrophosphates were revealed.

[The biometric analysis of bacteria in soil]. / Biometricheskii analys kletok bakterii v pochve.

The biometric analysis of bacterial cells in soil by light, fluorescence, and scanning electron microscopy showed that their average size is 0.8 micron in diameter, 1.4 microns in length, and 0.7 micron 3 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. It is the first experimental evidence showing that the metabolic activity of soil bacteria and their concentration and allometric parameters are related.

[Effect of butyric acid on physiologic activity of carbohydrate-oxidizing rhodococci]. / Vlianie maslianoi kisloty na fiziologicheskuiu aktivnost' uglevodorodokisliaiushchikh rodokokkov

Laboratory experiments showed that butyric acid not only fails to meet the trophic requirements of hydrocarbon-oxidizing microorganisms, but even specifically inhibits their assimilatory and dissimilatory activity. Therefore, butyric acid can be referred to as growth inhibitors. The combined mineralization of carbohydrates and hydrocarbons can be described as follows. Plants polymers are converted to monosugars by heterotrophic soil microorganisms. As the concentration of the monosugars grows and oxygen becomes deficient, the monosugars are no longer oxidized completely but are fermented. As a result, glucose transforms to butyric acid, which inhibits hydrocarbon-oxidizing bacteria. It is concluded that, to be efficient, the cleanup of oil-contaminated soils must include measures to intensify the mineralization of carbohydrates and to inhibit their fermentation.

[Radial growth rate of soil Micromycetes colonies under different conditions of nitrogen nutrition]. / Radial'naia skorost' rosta kolonii pochvennykh mikromitsetov v razlichnykh usloviiakh azotnogo pitaniia.

The radial growth rate of soil micromycetes colonies as a function of mineral nitrogen concentrations in the medium is expressed by a bell-shaped curve. Low nitrogen concentrations are growth-limiting whereas its high concentrations inhibit the growth. Soil micromycetes differ in the absolute values of growth rates and in the ranges of tolerance.

[Structure of a primed microbial community as an integral method of evaluating the microbiologic state of soil]. / Struktura initsiirovannogo mikrobnogo soobshchestva kak integral'nyi metod otsenki mikrobiologicheskogo sostoianiia pochvy.

The paper describes a laboratory method of initiated microbial cenosis which makes it possible to evaluate the microbiological state of soil and to predict its change under the action of various anthropogenic factors. To this end, the structure and characteristics of a microbial cenosis initiated by a substrate are studied using a scanning electron microscope in combination with classical techniques of microbiology: the actual predominance and proportions of individual microbial groups (bacteria, actinomycetes, fungi, algae, protozoa and microscopic invertebrates); the interaction and interrelation between individual microbial populations in the cenosis; the biological properties of predominating microorganisms; the ratio between active and resting forms; the rate and character of growth of individual microbial populations in the cenosis and their succession. All these indices taken together may serve as a criterion for integral evaluation of the effect produced by various physico-chemical factors on the microbiological state of soil.

[Microbial cenosis in the initial stage of spruce needle decomposition]. / Mikrobnoe soobshchestvo v nachal'noi stadii razlozheniia khvoia eli.

The formation of saprophytic microbial cenosis at the primary stage of decomposition of spruce needles was studied by the method of scanning electron microscopy with parallel inoculations into growth media. The composition of the cenosis was found to differ depending on whether the needles were decomposed on the surface of the forest floor or on the soil without any flooring. The characteristics of the formation of the saprophytic microbial cenosis are described. The cenosis is formed from individual species of the soil microbial complex and from some representatives of the epiphytic microbial cenosis which change here becoming saprophytes instead of biotrophs. Yeasts and yeast-like organisms predominate at the primary stage of decomposition of spruce needles.

[Growth of epiphytic and soil yeasts on wheat seedlings]. / Razvitie épifitnykh i pochvennykh drozhzhei na prorostkakh pshenitsy.

Colonization of wheat seedlings by epiphytic (Rhodotorula glutinis) and soil (Lipomyces starkeyi) yeasts was studied by scanning electron microscopy. Epiphytic yeast cells dominated on the plant surface. Soil yeast cells were randomly distributed among both the zones of a seedling and the particles of an inorganic substrate. It has been found that epiphytic yeast strains can readily grow on the surface of a plant.

[Relationship between adsorption of microorganisms and the stage of their development]. / Adsorbtsiia mikroorganizmov v sviazi a étapami ikh razvitiia.

Bond strength during adsorption of microorganisms depends on their growth stages, as was found by light optical and scanning electron microscopy. The strenth of adsorption often decreases as a culture growth on the surface of an adsorbent. Adsorption of microorganisms is an important ecological process. Under favourable conditions, microorganisms grow at a high rate when they are firmly bound to a solid surface. After abundant growth which deteriorates their microenvironment, microorganisms desorb and are dispersed. Such is a distribution of microorganisms growing on solid surfaces.