[Microbial communities and their ability to oxidize n-alkanes in the area of release of gas- and oil-containing fluids in Mid-Baikal (Cape Gorevoi Utes)].

The microbial community in the area of oil seep in Mid-Baikal (Cape Gorevoi Utes) was studied. The number of microorganisms that oxidize normal hydrocarbons, petroleum, and easily accessible organic matter in the water mass of the lake, bottom sediments, and bitumen structures was studied in 2005-2009. The high heterogeneity of the distribution of microorganisms associated with the deparaffination of oil in the areas of oil seeps was noted. The maximum concentrations of hydrocarbon-oxidizing microorganisms in the samples of bottom water above bitumen structures (up to 2200 +/- 175 CFU/ml) and in bitumen structures themselves (up to 170000 +/- 13000 CFU/g) were determined. A model experiment showed that in the conditions of low temperatures (4 degrees C) the degradation of the fraction of oil n-alkanes by the natural microbial community reaches 90% over a period of 60 days.

[Effect of different calcium hypochlorite concentrations on the survival of potentially pathogenic microorganisms isolated from Baikal Lake].

The survival rate of bacteria of the genera Pseudomonas and Enterococcus isolated from Baikal Lake, exposed to different concentration of calcium hypochlorite used as a main agent for drinking water disinfection, was studied. Experimental studies have shown that chlorination was imperfect as this method is not always effective against Enterococci.

[Distribution of strains of spore-forming bacteria of the genus Bacillus in the bottom sediments of Lake Khubsugul in Northern Mongolia as an indication of paleoclimate].

Data on the distribution and abundance of bacteria of the genus Bacillus in the bottom sediments of Lake Khubsugul have shown the predominance of strains that preferred low temperatures. This indicates fairly cold temperature conditions on the territory of the Khubsugul drainage area. On the whole, the dynamics of interchange of minimums and maximums of abundance of bacteria of the genus Bacillus is similar to the global climate fluctuations. Study of the enzymatic activity of pure cultures revealed that most strains studied possessed proteolytic activity; consequently, the dynamics of bacteria development is correlated with the supply of organic nitrogen-containing compositions.

[Study on the Lake Baikal microbial community in the areas of the natural oil seeps].

We studied the composition of a natural microbial community, the distribution of different groups of microorganisms (including those able to degrade oil hydrocarbons) within the areas of natural oil seeps in the Lake Baikal. It was revealed that, in the bottom sediments, the oil-degrading microorganisms dominating the community have included the bacteria of g. Bacillus, while in the water column, dominating microbes are presented by species of genera Rhodococcus Pseudomonas, and Micrococcus. Under the conditions of the model experiment, the potential activity of Baikal microbes towards utilization of n-alcanes has been assessed. Under such conditions it was shown that the concentration of n-alcanes decreases to 60% during 20 days of the experiment (the initial oil concentration was 0.5 mg/l, i.e., ten maximal permissible concentrations, MPC).

[Degradation of bis(2-ethylhexyl)phthalate by microorganisms of water and sediments of the Selenga river and Baikal Lake under experimental conditions]. / Degradatsiia bis-(2-étilgeksil)ftalata mikroorganizmami vody i donnykh osadkov r. Selengi i oz. Baikal v usloviiakh model'nogo éksperimenta.

Degradation of bis-(2-ethylhexyl)phthalate (BEHP) by microbial associations of water and bottom sediments of the Selenga River and Lake Baikal and by pure cultures of microbial species belonging to various taxa isolated from the sediments under discussion has been studied. It has been shown that intense biological degradation occurs in both water and sediments. The degrees of conversion in experimental closed systems on minimal media are 46 and 24%, respectively. The most active of the organisms studied is a Micromironospora actinomycete. It degraded BEHP by 36% of its initial concentration. Spore-forming bacteria and microorganisms of the genus Pseudomonas were less active (17-23% and 7-11%).

[Effectiveness of erythrocytic diagnostic reagents in indicating Shigellae]. / Effectivnost' éritrotsitarnykh diagnostikumov pri indikatsii shigell.

The possibility of the preparation of dysentery antibody diagnostic reagents on the basis of adsorbed sera is shown. Such diagnostic reagents permit to determine 200000-600000 microbial bodies or 0.0008-0.0016 microgram of the antigen per ml. The use of antigenic erythrocytic diagnostic reagents for the indication of shigellae is expedient in the second variant of the passive hemagglutination inhibition test in the following modification: immune sera should be diluted not 2-fold, but only 1.5-fold; the material to be tested for the presence of shigellae should be added to these dilutions in a double volume.