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Interactions of the main components of microbial planktonic food web (bacteria, heterotrophic nanoflagellates, and viruses) were studied in a protected overgrown littoral zone of the Rybinsk Reservoir (Upper Volga).. The effect of bird colonial, settlements (the Laridae family) on these processes was deter- mined. The following systems exhibited significant negative correlations: "heterotrophic nanoflagellates- large rod-shaped bacteria" ("predator-prey"), "viruses-bacteriophages-bacterial products" ("parasite-. host") and "heterotrophic nanoflagellates-viruses-bacteriophages." Relations between biotic factors con- trolling bacterial development were more pronounced outside the zone affected by colonial bird settlements. Near the bird colony the role of viruses in mortality of planktonic bacteria increased. Reproduction of bacte- rial cells accelerated in response to the increase in feeding activity of heterotrophic nanoflagellates. Viruses- bacteriophages and heterotrophic nanoflagellates probably eliminate different targets until medium-sized cells become predominant in the bacterial community. Then heterotrophic nanoflagellates consume bacterial cells infected with viruses.

Aim: Study the effect of water temperature from 40 to 70 degrees C on viability of plankton forms and model Legionella pneumophila under experimental conditions., Materials and Methods: Monospecies legionella biofilms, obtained in plates for enzyme immunoassay during 96 hours at 28 degrees C, and water suspension of BCYE agar cultivated cells of L. pneumophila at a concentration of 10(3) - 10(5) CFU per liter were used in the study for evaluation of bactericidal effect of temperature on various legionella forms., Results: Analysis of effects of various temperature regimens on plankton forms and model legionella biofilms has shown that at a temperature range from 50 to 60 degrees C a significant reduction of quantity of viable legionella cells occurs. Model legionella biofilms have partially conserved viability at a temperature of 60 degrees C and only exposition to a temperature of 70 degrees C resulted in death of legionella biofilms and plankton forms of bacteria. A dependence of viability conservation of legionella from the initial concentration of the causative agent in water and duration of exposition at varying temperature was shown., Conclusion: Short-term heating at a temperature of at least 70 degrees C has the most pronounced bactericidal effect on plankton forms and model L. pneumophila biofilms under experimental conditions. Such temperature regimen could be used as one of the prophylaxis approaches during maintenance of especially dangerous water system and, fist of all, systems of hot water supply.

For the Pechora sea, according to microbiological shootings during winter seasons 2002-2005, the analysis of conditions forming of an abundance winter bacterial communities a plankton is carried out. For the outlined varieties of waters, regularities of distribution of segregate groups bacterial communities are discussed. The natural modification of microbiologic indicators ona gradient of parametres a physical and chemical complex is shown. In subglacial conditions average number bacterioplankton 234 thousand in cell/ml, cellular volume - 0.58 μm3, at square of 550 mm2/L. A biomass store a stratum of probed harbour area Pechora sea of 0-25 m to 187 x 10(90 G.

Lipolytic and catalase activity of bacteria-destructors of protective coatings at different growth models: biofilm and plankton have been studied. It was shown that the synthesis of exoenzymes in the biofilm is different. Activity of extracellular lipase and catalase in the biofilm is 1.1-1.5 and 1.2-2.1 times higher, respectively, than in plankton. The experiment duration being increased to 14 days, the lipolytic activity considerably decreases. Activity of studied enzymes, produced by bacteria-destructors, can be used for estimating bioresistance of isolating coatings as the index of their biodegradation in technogenic media.

The microbial community of Baikal sponges has been studied in five species belonging to the genera Swartschewskia, Baicalospongia, and Lubomirskia of the endemic family Lubomirskiidae. The results show that the total numbers of bacteria and bacterioplankton production have an effect on the growth of L. baicalensis body. Bacteria of the genera Pseudomonas, Bacillus, Micrococcus, Sarcina, Flavobacterium, Arthrobacter, and Acinetobacter living in the sponges are representatives of the Baikal bacterioplankton. Actinomycetes of the genera Streptomyces and Micromonospora are a permanent component of the cultivable sponge microbial community. The numbers and enzyme activities of heterotrophic, oligotrophic, and psychrophilic bacteria isolated from different sponge species and the surrounding water in autumn and in winter have been estimated.

Differently directed effects from autochthonous algae and bacteria on allochthonous microflora in hyperosmotic conditions were revealed and analyzed. Living halophilic microorganisms increase survival time of enterobacteria. Cellular extracts from halophils decrease storage time of allochthonous bacteria in a highly mineralized medium. Allochthonous bacteria in hyperosmotic conditions are able to suppress viability of autochthonous halophilic microflora. Symbiotic interactions between autochthonous and allochthonous microorganisms, defined by correlation of protective and antagonistic effects, regulate survival of microorganisms in hyperhaline water reservours and can be used for the assessment of their ecological and sanitary-and-hygienic states.

The role of enzyme--substrate interactions for the survival of bacteria in natural biocenoses has been analyzed with the systems "lysozyme-antilysozyme", "histon-antihiston" used as models. The conception of a possible universal mechanism for supporting the circulation of pathogenic and opportunistic microorganisms among eukaryotes, irrespective of their evolutionary status and environment, has been formulated. This mechanism is ensured by the natural resistance of the eukaryotic cells and by persistence factors on the part of the pathogen; as a result, the dynamic system of interactions is formed which facilitates the survival of microorganisms due to their persistence potential. New knowledge thus obtained opens prospects in the study of sanitary and ecological aspects of water biocenoses.

The enumeration of actively respiring bacterial cells in different biotopes of the littoral zone of the Rybinsk Reservoir during the spring period of ice thaw using the fluorescent dye 5-cyano-2,3-ditolyl tetrazolium chloride showed that bacterial communities growing on the bottom surface of the ice cover and in water overgrown by higher aquatic plants were most active. The number of active cells among individual bacterial cells averaged 20% and reached about 40% among aggregated and filamentous bacterial cells. The results of the count of active bacteria by this method were compared with those obtained by other methods.