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M V Ivanov

Publications and source records attributed to M V Ivanov.

At least 55 records · Page 3Linked to original sources
PubMedDate not supplied

[Phylogenetic diversity of aerobic saprotrophic bacteria isolated from the Daqing oil field].

A diverse and active microbial community in the stratal waters of the Daqing oil field (China), which is exploited with the use of water-flooding, was found to contain aerobic chemoheterotrophic bacteria (including hydrocarbon-oxidizing ones) and anaerobic fermentative, sulfate-reducing, and methanogenic bacteria. The aerobic bacteria were most abundant in the near-bottom zones of injection wells. Twenty pure cultures of aerobic saprotrophic bacteria were isolated from the stratal waters. Under laboratory conditions, they grew at temperatures, pH, and salinity values typical of the stratal water from which they were isolated. These isolates were found to be able to utilize crude oil and a wide range of hydrocarbons, fatty acids, and alcohols. Phylogenetic analysis carried out with the use of complete 16S rRNA sequences showed that the isolates could be divided into three major groups: gram-positive bacteria with a high and a low G + C content of DNA and gram-negative bacteria of the gamma-subclass of the Proteobacteria. Gram-positive isolates belonged to the genera Bacillus, Brevibacillus, Rhodococcus, Dietzia, Kocuria, Gordonia, Cellulomonas, and Clavibacter. Gram-negative isolates belonged to the genera Pseudomonas and Acinetobacter. In their 16S rRNA sequences, many isolates were similar to the known microbial species and some probably represented new species.

Alcohols↗
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[Geochemical characteristics of the carbonate constructions formed during microbial oxidation of methane under anaerobic conditions].

The aragonite constructions of the Black Sea are formed in a stable anaerobic zone and are a perfect object to study the natural mechanism of anaerobic methane oxidation. The most probable pathway of methane oxidation is its methanogen-mediated reaction with bicarbonates, dissolved in seawater, with the formation of water and acetate, which is then consumed by other components of the anaerobic community. Comparison of the delta 13C values of carbonate minerals and organic matter once more demonstrated that the formation of the organic matter of biomass is accompanied by intense fractionation of carbon isotopes, as a result of which the total organic matter of biomass acquires an extremely light isotopic composition, characterized by delta 13C values as low as -83.8@1000.

Acetates↗
PubMedDate not supplied

[Biogeochemical cycle of methane in the northwestern shelf of the Black Sea].

Seasonal investigations of methane distribution and rates of its oxidation and generation in the water column and sediments of the Black Sea northwestern shelf were carried out within the framework of the interdisciplinary projects "European River-Ocean Systems" (EROS-2000, EROS-21) and "Biogenic Gases Exchange in the Black Sea" (BigBlack) in August 1995, May 1997, and December 1999. Experiments that involved the addition of 14CH3COONa and 14CO2 to sediment samples showed the main part of methane to be formed from CO2. Maximum values of methane production (up to 559 mumol/(m2 day)) were found in coastal sediments in summer time. In winter and spring, methane production in the same sediments did not exceed 3.6-4.2 mumol/(m2 day). The delta 13C values of methane ranged from -70.7 to -81.8@1000, demonstrating its microbial origin and contradicting the concept of the migration of methane from cold seeps or from the oil fields located at the Black Sea shelf. Experiments that involved the addition of 14CH4 to water and sediment samples showed that a considerable part of methane is oxidized in the upper horizons of bottom sediments and in the water column. Nevertheless, it was found that, in summer, part of methane (from 6.8 to 320 mumol/(m2 day)) arrives in the atmosphere.

Methane↗
PubMedDate not supplied

[Fractionation of stable sulfur isotopes during microbiological processes in Slavyansk lakes].

The isotopic content of sulphur in sulphates increases with depth in waters containing hydrogen sulphide of the meromictic lakes Repnoe and Veisovo as a result of microbiological reduction of sulphates. At the same time, hydrogen sulphide enrichments 19 to 25% of the light isotope 32S in the lake Veisovo, and 24 to 32% in the lake Repnoe. The fractionation of sulphur isotopes, manifested in the enrichment of sulphides with lighter isotopes, and that of sulphates with heavier isotopes, was found also in the bottom deposits of the lake Repnoe. The isotope and microbiological data suggest that, in the zone of mass growth of the phototrophic sulphur bacteria in the lake Repnoe, there are two processes of fractionation: (a) due to the bacterial reduction of sulphates; and (b) due to anaerobic oxidation of hydrogen sulphide, resulting in the enrichment of hydrogen sulphide with the light isotope 32S by 5 to 7 promille.

Bacteria↗
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[Dynamics of microbial processes in the stratal waters of the Romashkinskoe oil field].

Dynamics of the microbial processes developing in parallel with the exploitation of the Romashkinskoe oil field (Tatarstan) was studied in two areas differing in the degree of stratal water freshening. Flooding the strata in conjunction with purposeful measures on stratal microflora activation was shown to increase the microbial population density and activate both methanogenesis and sulfate-reduction; the latter process was limited by the low sulfate concentration. Development of anaerobic processes correlated with changes in acetate concentration in the stratal water. High mineralization (over 200 g/l) inhibited the stratal water microflora even if other conditions were favorable. Isotopic analysis of the carbonate carbon showed that the bicarbonate concentration increased in the stratal water due to microbial degradation of oil hydrocarbons and further participation of the biogenic carbon dioxide in dissolution of the carbonate cement of the oil-bearing strata. In strongly desalinated stratal water, the proportion of the newly formed bicarbonate was as high as 80%.

Acetates↗
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[Radioisotope method of determining the intensity of bacterial methane formation].

The rate of methane formation by bacteria was determined by the isotope tracer technique using labeled carbon in the form of bicarbonate. The rate of methane production in the ooze deposits of the Kuznechikha lake was calculated by this technique to constitute 7.46 to 7.70 cm3 CH4 per 1 litre per day. The rate of the process was shown to depend on the number of methane-producing bacteria.

Bacteria↗
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[Determination of the rate of microbiological oxidation of methane using 14CH4].

The rate of microbiological oxidation of methane was determined by a technique using 12CH4. About 75-96 percent of the carbon form the methane oxidized by microorganisms was found in carbon dioxide, the remaining part was incorporated into the microbial cells. The rate of microbiological mehtane oxidation in the water of the Mari lakes was 6.4 times 10(-3) to 464.4 times 10(-3) cm3 CH4/litre per day.

Bacteria↗
PubMedDate not supplied

[Production of oil-processing compounds by microorganisms from the Daqing oil field, China].

Twenty pure cultures isolated from formation waters of the Daqing oil field were studied with respect to their capacity to produce surface-active compounds in media with individual hydrocarbons, lower alcohols, and fatty acids. Aerobic saprotrophic bacteria belonging to the genera Bacillus, Brevibacillus, Rhodococcus, Dietzia, Kocuria, Gordonia, Cellulomonas, Clavibacter, Pseudomonas, and Acinetobacter decreased the surface tension of cultivation media from 55-63 to 28-44 mN/m. Strains of Bacillus cereus, Rhodococcus ruber, and Bacillus licheniformis produced biosurfactants most actively. Bacteria of the genera Rhodococcus, Dietzia, Kocuria, and Gordonia produced exopolysaccharides in media with hydrocarbons. Culture liquids of the strains of R. ruber and B. licheniformis exhibited oil-releasing effect. Thus, the Daqing oil field is inhabited by aerobic bacteria capable of producing effective oil-releasing agents.

Alcohols↗
PubMedDate not supplied

[Microbial metabolism of the carbon and sulfur cycles in Shira Lake (Khakasia)].

Microbiological and biogeochemical studies of the meromictic saline Lake Shira (Khakasia) were conducted. In the upper part of the hydrogen-sulfide zone, at a depth of 13.5-14 m, there was a pale pink layer of water due to the development of purple bacteria (6 x 10(5) cells/ml), which were assigned by their morphological and spectral characteristics to Lamprocystis purpureus (formerly Amoebobacter purpurea). In August, the production of organic matter (OM) in Lake Shira was estimated to be 943 mg C/(m2 day). The contribution of anoxygenic photosynthesis was insignificant (about 7% of the total OM production). The share of bacterial chemosynthesis was still less (no more than 2%). In the anaerobic zone, the community of sulfate-reducing bacteria played a decisive role in the terminal decomposition of OM. The maximal rates of sulfate reduction were observed in the near-bottom water (114 micrograms S/(1 day)) and in the surface layer of bottom sediments (901 micrograms S/(dm3 day)). The daily expenditure of Corg for sulfate reduction was 73% of Corg formed daily in the processes of oxygenic and anoxygenic photosynthesis and bacterial chemosynthesis. The profile of methane distribution in the water column and bottom sediments was typical of meromictic reservoirs. The methane content in the water column increased beginning with the thermocline (7-8 m), and reached maximum values in the near-bottom water (17 microliters/l). In bottom sediments, the greatest methane concentrations (57 microliters/l) were observed in the surface layer (0-3 cm). The integral rate of methane formation in the water column and bottom sediments was almost an order of magnitude higher than the rate of its oxidation by aerobic and anaerobic methanotrophic microorganisms.

Carbon↗
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[Intensity of bacterial methane formation in ooze deposits in lakes].

The rate of methane production of bacteria via the decomposition of acetate in ooze deposits of the Mari lakes was 0.0165 to 0.483 mg CH4/day/ litre wet ooze. From 32 to 98 per cent of methane in the ooze of studied reservoirs formed through microbiological reduction of carbon dioxide by hydrogen.

Acetates↗
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[Microbial sulfate reduction in sediments of the coastal zone and littoral of the Kandalaksha bay of the White sea].

Microbiological and biogeochemical investigations of the coastal zone and the littoral of the Kandalaksha Bay of the White Sea were carried out. The material for investigations was obtained in the series of expeditions of the Institute of Microbiology, Russian Academy of Sciences, in August 1999, 2000, 2001, and in March 2003. The studies were conducted on the littoral and in the water area of the Kandalaksha Preserve, the Moscow University Belomorsk Biological Station, and the Zoological Institute Biological Station, Russian Academy of Sciences, Sediment sampling on the littoral was carried out in the typical microlandscapes differing in the sediment properties and macrobenthos distribution. The maximal sulfate reduction rate (SRR) was shown for the shallow part of the Chemorechenskaya Bay (up to 2550 micrograms S/(dm3 day)) and in the Bab'ye More Bay (up to 3191 micrograms S/(dm3 day)). During the winter season, at a temperature of -0.5-0.5 degrees C, the SRR in the sediments of the Kartesh Bay was 7.9-13 micrograms S/(dm3 day). In the widest limits, the SRR values varied in the sediment cores sampled on the littoral. The minimal values (11 mu]g S/(dm3 day)) were obtained in the core samples on the silt-sandy littoral. The littoral finely dispersed sediments rich in organic matter were characterized by high SRR values (524-1413 micrograms S/(dm3 day)). The maximal SRR values were shown for the sediments present within the stretch of decomposing macrophytes, in local pits at the lower littoral waterline, and in the mouth of a freshwater stream (51-159 mg S/(dm3 day)). A sharp difference in the level of H2S production in the type microlandscapes was shown. The average hydrogen sulfide production in finely dispersed sediments constituted 125 mg S/(m2 day); in stormy discharge deposits, 1950 mg S/(m2 day); in depressions under stones and in silted pits, 4300 mg S/(m2 day). A calculation made with regard to the area of microlandscapes with increased productivity shows that the daily H2S production per 1 km2 of the littoral (August) is 60.8 to 202 kg S/(km2 day), while the organic carbon consumption for sulfate reduction per 1 km2 of the littoral is 46 to 152 kg C(org)/(km2 day).

Ecosystem↗
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[Methane content in bottom sediments and water mass of the Black Sea].

The methane content in bottom sediments and water column of the Black Sea was determined using various methods of desorption and analysis of gases and various methods of calculating their concentrations. The head-space method with the use of salting out and calculation by internal standard proved to be the most accurate procedure for the analysis of methane concentration in bottom sediments. The methane content in bottom sediments increased with the depth of sediment sampling. In the upper 50-70 cm of shelf sediments, two minimums of methane concentration were revealed; in deep-sea sediments, only one minimum was recorded (in the 20-50 cm horizons). In the water column, methane concentrations slowly grew from the surface to a depth of 150-200 m and abruptly increased to a depth of 700-1200 m, remaining virtually constant in underlying layers. In certain deep-sea regions, peaks of methane content in the 1000-1200 m horizons of the water column were revealed, which were most probably due to local influx of abyssal waters enriched with this gas.

Geologic Sediments↗
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[Intensities of microbial production and oxidation of methane in bottom sediments and water mass of the Black Sea].

Intensities of biogeochemical (microbial) processes of methane production and methane oxidation were determined in bottom sediments and water column of the Black Sea. Aerobic bacterial oxidation of methane is confined to the upper 20-30 cm of Holocene bottom sediments of the shelf (0.7-259 ng C/(dm3 day)) and oxygenated waters (0.2-45 ng C/(dm3 day)). In reduced sediments of the deep-sea zone and in the hydrogen sulfide-containing water column, considerable intensities of anaerobic methane oxidation were recorded, comparable to or exceeding the intensities of methane oxidation in oxygenated layers. From one fourth to one half of the methane formed in bottom sediments was oxidized immediately therein. The major part of the remaining methane was oxidized in the water column, and a smaller portion arrived in the atmosphere.

Bacteria↗
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[Microbiological oxidation of methane in the stratal waters of the Lower Volgian].

Methanotrophic bacteria are rather widely distributed in bed waters of oil and gas deposits in the Nizhneye Povolzhye. Their number reaches 250 cells per 1 ml of water. However, bacterial methane oxidation is active only in waters whose redox potential exceeds +250 mV. In a number of cases, microbial methane oxidation is limited by the absence of oxygen from bed waters. If air is added to samples of such water, methane dissolved in the water is oxidized by microorganisms at a high rate (2--451 X 10(-4) cm3 of methane per litre of water per day).

Geological Phenomena↗
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[The biogeochemical cycle of methane in the coastal zone and littoral of the Kandalaksha Bay of the White Sea].

Microbiological and biogeochemical investigations of the processes of methane production (MP) and methane oxidation (MO) in the coastal waters and littoral of the Kandalaksha Bay of the White Sea were carried out. The studies were conducted in the coastal zones and in the water areas of the Kandalaksha Preserve, Moscow University White Sea Biological Station, and Zoological Institute (RAS) Biological Station in August, 1999, 2000, and 2001 and in March, 2001. The rate of CO2 assimilation in the shallow and littoral sediments was 35-27800 microg C/(dm3 day) in summer and 32.8-88.9 microg C/(dm3 day) in winter. The maximal rates of MP were observed in the littoral sediments in the zone of macrophyte decomposition, in local depressions, and in the estuary of a freshwater creak (up to 113 microl/(dm3 day)). The maximal level of MO was observed in the shallow estuarine sediments (up to 2450 microl/(dm3 day)). During the winter season, at the temperature of -0.5 to 0.5 degrees C, the MP rate in the littoral sediments was 0.02-0.3 microl/(dm3 day), while MO rate was 0.06-0.7 microl/(dm3 day). The isotopic data obtained indicate that the C(org) of the mats and of the upper sediment layers is enriched with the heavy 13C isotope by 1-4 per thousand as compared to the C(org) of the suspension, comprised on 33.5-34.3% of phytoplankton. A striking difference was found between the levels of methane emission by the typical littoral microlanscapes. In fine sediments, the average emission was 675 microl CH4/(m2 day), in the stormy discharge stretch sediments it was 1670 microl CH4/(m2 day), and under the stones and in silted pits, 1370 microl CH4/(m2 day). The calculation performed with consideration of the microlandscape areas with a high production allowed the CH4 production of 1 km2 of the littoral to be estimated as 192-300 1 CH4/(km2 day).

Bacteria↗