Destruction of chlorinated derivatives of phenol: ortho-chlorophenol, para-chlorophenol, and 2,4-dichlorophenoxyacetic acid by bacteria communities in anaerobic sludge

The bacterial community of anaerobic sludge could degrade ortho-chlorophenol, para-chlorophenol, and 2,4-dichlorophenoxyacetic acid at concentrations as high as 100 mg/l. The time needed for the degradation of a given chlorinated phenol derivative increased 1.5- to 2-fold upon a twofold increase in its concentration (from 50 to 100 mg/l). The duration of the adaptation period depended on the compound studied and on its concentration. The degradation of 2,4-dichlorophenoxyacetic acid proceeded via 2,4-dichlorophenol and p-chlorophenol as intermediates; the degradation of o-chlorophenol occurred with the formation of phenol. The dynamics of p-chlorophenol degradation and chloride ion accumulation were studied.     

Methanotrophs of the psychrophilic microbial community of the Russian Arctic tundra

In tundra, at a low temperature, there exists a slowly developing methanotrophic community. Methane-oxidizing bacteria are associated with plants growing at high humidity, such as sedge and sphagnum; no methonotrophs were found in polytrichous and aulacomnious mosses and lichens, typical of more arid areas. The methanotrophic bacterial community inhabits definite soil horizons, from moss dust to peat formed from it. Potential ability of the methanotrophic community to oxidize methane at 5 degrees C enhances with the depth of the soil profile in spite of the decreasing soil temperature. The methanotrophic community was found to gradually adapt to various temperatures due to the presence of different methane-oxidizing bacteria in its composition. Depending on the temperature and pH, different methanotrophs occupy different econiches. Within a temperature range from 5 to 15 degrees C, three morphologically distinct groups of methanotrophs could be distinguished. At pH 5-7 and 5-15 degrees C, forms morphologically similar to Methylobacter psychrophilus predominated, whereas at the acidic pH 4-6 and 10-15 degrees C, bipolar cells typical of Methylocella palustris were mostly found. The third group of methanotrophic bacteria growing at pH 5-7 and 5-10 degrees C was represented by a novel methanotroph whole large coccoid cells had a thick mucous capsule.     

A psychrotolerant Caulobacter sp. from Russian polar tundra soil

Strain Z-0024, a psychrotolerant aerobic heterotrophic representative of the prosthecate bacteria of the genus Caulobacter, was isolated from a methanotrophic enrichment obtained from Russian polar tundra soil. The cells of the new isolate are vibrios (0.5-0.6 x 1.3-1.8 microm) with a polar stalk. The organism grows in a temperature range from 5 to 36 degrees C, with an optimum at 20 degrees C. The pH range for growth is from 4.5 to 7.0 with an optimum at pH 6.0. Strain Z-0024 utilizes a wide range of organic compounds: sugars, amino acids, volatile fatty acids, and primary alcohols. It tolerates a NaCl concentration in the medium of up to 15 g/l. The G + C content of DNA is 66.6 mol %. The 16S rRNA gene sequence analysis revealed that strain Z-0024 belongs to the cluster of Caulobacter species, showing a 98.8-99.2% sequence similarity to them. DNA-DNA hybridization revealed a low level of homology (24%) between strain Z-0024 and C. vibrioides ATCC 15252. The new isolate is described as Caulobacter sp. Z-0024.     

The processes of methane formation and oxidation in the soils of the Russian arctic tundra

Methane emission from the following types of tundra soils was studied: coarse humic gleyey loamy cryo soil, peaty gley soil, and peaty gleyey midloamy cryo soil of the arctic tundra. All the soils studied were found to be potential sources of atmospheric methane. The highest values of methane emission were recorded in August at a soil temperature of 8-10 degrees C. Flooded parcels were the sources of atmospheric methane throughout the observation period. The rates of methane production and oxidation in tundra soils of various types at 5 and 15 degrees C were studied by the radioisotope method. Methane oxidation was found to occur in bog water, in the green part of peat moss, and in all the soil horizons studied. Methane formation was recorded in the horizons of peat, in clay with plant roots, and in peaty moss dust of the bogey parcels. At both temperatures, the methane oxidation rate exceeded the rate of methane formation in all the horizons of the mossy-lichen tundra and of the bumpy sinkhole complex. Methanogenesis prevailed only in a sedge-peat moss bog at 15 degrees C. Enrichment bacterial cultures oxidizing methane at 5 and 15 degrees C were obtained. Different types of methanotrophic bacteria were shown to be responsible for methane oxidation under these conditions. A representative of type I methylotrophs oxidized methane at 5 degrees C, and Methylocella tundrae, a psychroactive representative of an acidophilic methanotrophic genus Methylocella, at 15 degrees C.     

Effect of gene db dose on the development of beta-cytotropic and immunotropic effects of long-term glibenclamide administration in C57BL/KsJY mice]

The studies have revealed a modifying influence of gene db on the expressivity of damaging beta-cytotropic effect of long-term sulphanilamide therapy and on the development of autoimmune cell response to antigens of pancreatic islets. It is substantiated as promising to study a significance of individual genes and their doses in determining the variations of reactivity to beta-cytotropic and immunotropic effects of the chemical nature factors.     

The multilayer growth of epithelium-like ESK cells in perfused cultures]

The multilayer growth of an epithelium-like ESK [correction of SPEV] cell culture was achieved under condition of culture medium perfusion. The growth of the ESK [correction of SPEV] cells is described under conditions excluding medium movement above the cells in the chamber with a semipermeable membrane separating the cells from the perfused medium. Under these conditions the multilayer (30-40 layers) growth of culture was observed. The data observed are in favour of our suggestion that it is the diffusional limitations in mass exchange, rather than intracellular interaction contacts, that may be responsible for cell growth in culture. A dependence of culture growth on the initial inoculation density, under condition of medium perfusion immediately above the cells, was determined. The dependence of the multilayer saturation density on the perfusion rate and on the complete replacement of the perfused medium is discussed. The existence of a limiting saturation density of perfused culture was shown.