[Butyric acid bacteria of the genus Clostridium in the bottom sediments of inland basins of different types].

The cell numbers and ecological characteristics of the distribution of certain species of butyric acid bacteria (BAB) of the genus Clostridium in the bottom sediments of inland basins of different types were studied using the optimal nutrient media. The seasonal dynamics of clostridial vegetative cells and spores in sediments with different ecological conditions were revealed. The cell numbers of the dominant BAB species were shown to depend on the redox potential of the sediments, the amount and composition of C(org), and the trophic state of the basin in general. C. pasteurianum was found to predominate in eutrophic lakes and reservoirs (5-11 x 10(6) cells/cm3), C. butyricum and C. felsineum predominated in mesotrophic ones (2-11 x 10(6) cells/cm3), and C. acetobutylicum was predominant in acidic chthionoeutrophic lakes and reservoirs (0.1-0.5 x 10(6) cells/cm3). The lowest cell numbers of BAB were found in river sediments, whereas the highest numbers were recorded in the sediments of polysaprobic zones (0.1-1.0 x 10(3) and 0.5-2.0 x 10(7) cells/cm3 respectively).

[Bacterial quantity and microbial reactivity in Tugur bay of the Okhotsk Sea]. / Chislennost' bakterii i mikrobiologicheskie protsessy v vode Tugurskogo zaliva Okhotskogo moria.

The paper presents the results of investigation of the total abundance and the biomass of bacterioplankton, the abundance of heterotrophic bacteria, and the activity of microbiological processes involved in the carbon cycle in the water of the Bay of Tugur of the Sea of Okhotsk. In different regions of the bay, the total abundance of bacterioplankton was found to vary from 0.51 x 10(6) to 2.54 x 10(6) cells/ml; the bacterioplankton biomass, from 8.5 to 46.5 micrograms C/l; the abundance of heterotrophic bacteria, from 0.06 x 10(3) to 2.12 x 10(3) cells/ml; the bacterial assimilation of CO2, glucose, acetate, and protein hydrolysate, from 0.8 to 6.3, from 0.11 to 1.88, from 0.07 to 0.56, and from 0.01 to 0.22 mg C/(m3 day), respectively; the degradation of organic matter ranged from 28 to 221 mg C/(m3 day); and the intensity of methane oxidation, from 0.0005 to 0.17 microliter CH4/l. The spatial pattern and the functional characteristics of bacterioplankton in the Bay of Tugur were found to be dependent on the tidal dynamics.

[Bacterioplankton and bacteriobenthos of some floodplain lakes in the course of the lower Amur river]. / Bakterioplankton i bakteriobentos nekotorykh pripoimennykh ozer nizov'ia reki Amur.

The main structural and functional characteristics of bacterioplankton and bacteriobenthos of three lakes in the lower course of the Amur River are presented: the total number of bacteria (TNB), biomass, the numbers of bacteria of certain aerobic and anaerobic groups; the intensities of methanogenesis (MG), methane oxidation (MO), assimilation of 14C-compounds, sulfate reduction (SR); and gross estimate of organic matter decomposition (D). Depending on the reservoir type and the anthropogenic load, TNB constituted (2.27 to 16.1) x 10(6) cells/ml in water and (1.06 to 10.35) x 10(9) cells/ml in sediments; MO was 0 to 0.28 ml CH4/(1 day) in water and 0 to 8.4 ml CH4/(dm3 day) in sediments; MG in sediments was 0.001 to 40 ml CH4/(dm3 day); SR varied from 0.001 to 24.8 mg S/(dm3 day); D was 0.3 to 25 g C/(m2 day) in water and 0.2 to 4.9 g C/(m2 day) in sediments. The role of anaerobic microbial processes of organic matter decomposition was shown to increase with an increase in the anthropogenic load, attaining 95% of the total D in the ecosystem of an accumulating pond.

[Intensity of the microbiological processes of the methane cycle in different types of Baltic lakes]. / Intensivnost' microbiologicheskikh protsessov krugovorota metana v raznotipnykh ozerakh Pribaltiki.

The intensity of the microbiological processes of methane formation (MF) and methane oxidation (MO) was determined in the sediments and water of different types of Baltic lakes. The emission of methane from the lake sediments and methane distribution in the water column of the lakes were studied as functions of the lake productivity and hydrologic conditions. During summers, the intensity of MF in the lake sediments and waters varied from 0.001 to 106 ml CH4/(dm3 day) and from 0 to 3.2 ml CH4/(1 day), respectively, and the intensity of MO in the sediments and water varied from 0 to 11.2 ml CH4/(dm3 day) and from 0 to 1.1 ml CH4/(1 day), respectively. The total methane production (MP) in the lakes varied from 15 to 5000 ml CH4/(m2 day). In anoxic waters, the MP comprised 9-18% of the total PM in the lakes. The consumption of organic carbon for methanogenesis varied from 0.03 to 9.7 g/(m2 day). The role of the methane cycle in the degradation of organic matter in the lakes increased with their productivity.

[Fixation of molecular nitrogen and activity of the microflora in the bottoms of certain lakes in the Estonian SSR and the Rybinsk reservoir]. / Fiksatsiia molekuliarnogo azota i aktivnost' mikroflory v gruntakh nekotorykh ozer Estonskoi SSSR i Rybinskogo vodokhranilishcha.

The rate of molecular nitrogen fixation was determined in bottom grounds of three Estonian lakes and the Rybinsk water reservoir in the summer of 1977--1978. Certain species of nitrogen fixing bacteria were found to be confined to lakes of certain trophic type. Ecological niches with the mass growth of Clostridium pasteurianum, Azomonas agilis and Clostridium butyricum were detected in the sediments of eutrophic lakes. Ecological niches of Az. insignis and Cl. acetobutylicum occur in polyhumic lakes. Ecological niches for the nitrogen fixing microaerophilic organisms Methylosinus trichosporium, M. sporium and Mycobacterium flavum can be found in the sediments of water reservoirs of any trophic type. The important ecological factors which favour the growth of microflora with a high rate of molecular nitrogen fixation in bottom grounds are as follows: a sufficiently high temperature, a weakly alkaline reaction, the presence of oxygen in the water near the bottom, and the ratio of organic carbon to total nitrogen about 10--11. The destruction of organic substances in such sediments involves both aerobic and anaerobic microflora, and Cl. butyricum is abundant among nitrogen fixing microorganisms.

[Molecular nitrogen fixation in the waters of eutrophic and polyhuic lakes of the Estonian SSR]. / Fiksatsiia molekuliarnogo azota v vodnoi masse nekotorykh evtrofnykh i poligumoznykh ozer Estonskoi SSR.

A modified acetylene technique was used to assay the rate of molecular nitrogen fixation in Estonian lakes containing methane in the hypolimnion. Methods were elaborated to eliminate ethylene cooxidation by methane oxidizing bacteria. Methane oxidation and nitrogen fixation were found in a narrow microaerobic zone in lakes with the stratification of temperature in the water mass; these biochemical processes occurred when the content of dissolved oxygen varied within the range of 0.1 to 0.8 mg O2 per litre. The rate of these microbiological processes was significantly influenced by trophic relationships with microorganisms from the adjacent ecological niches. In the epilmnion of eutrophic lakes, atmospheric nitrogen was fixed by the blue-green algae Anabaena and Gloeocapsa minima and by the heterotrophic bacterium Azomonas agilis; in the microaerobic zone of metalimnion, atmospheric nitrogen was fixed by the methane oxidizing bacteria Methylosinus trichosporium and M. sporium and by the hydrogen oxidizing bacterium Mycobacterium flavum. In polyhumic lakes, nitrogen fixation was performed by the bactera Az. insignes, Methylosinus trichosporium, M. sporium and Mycobacterium flavum only in water layers near the bottom with microaerobic conditions.

[Number of butyric acid bacteria belonging to the genus Clostridium in the slimy sediments of Volga reservoirs]. / Kolichestvo maslianokislykh bakterii, otnosiashchikhsia k rodu Clostridium, v ilovykh otlozheniiakh vodokhranilishch Volgi.

The number of Clostridium pasteurianum, Cl. butyricum, and Cl. acetobutylicum was determined in ooze deposits of the Volga River reservoirs using enriched nutrient media. The bacterial number for the two former species was about 1 + 10(6) cells per 1 ml of ooze with a high content of easily assimilated organic substances, thus being by 1--3 orders of magnitude higher than for Cl. pasteurianum on media without nitrogen. The bacterial number for Cl. acetobutylicum was 0.1--1 + 10(3) cells per 1 ml.

[Molecular nitrogen fixation in eutrophic Beloye Ozero]. / Fiksatsiia molekuliarnogo azota v evtrofnom ozere Beloe.

The rate of production and mineralization of organic matter and the rate of fixation of molecular nitrogen were assayed in th eutrophic lake Beloye (near Moscow) at the end of summer stagnation (1976). The content of hydrogen sulphide reached 6.8 mg per litre which resulted in a change of the ecological environment in the lake. The fixation of molecular nitrogen in water layers was characterized by three maxima: 5.0 mcg N per litre per 4 hours (surface); 4.2 mcg N per litre per 4 hours (metalimnion) and 2.8 mcg N per litre per 4 hours (at bottom). The fixation of nitrogen in the trophogenous layer involved mainly the blue-green alga Anabaena. In the sulphide zone, molecular nitrogen was fixed by butyric and sulphate-reducing bacteria.