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ABSTRACT: The work is dedicated to searching for microorganisms of the domain Bacteria capable of dissimilatory sulfate reduction in the samples of microbial mats from a carbonate chimney in the Lost City hydro-thermal
field. Cloning of 16S rRNA genes, the universal phylogenetic marker, and dsrAB, the functional marker for sulfate reduction, revealed phylotypes related to spore-forming Desulfotomaculum. No members of the Deltaproteobacteria, comprising the most numerous bacterial group with demonstrated capacity for dissimilatory sulfate reduction, were found.
The phylogenetic position of 16S rRNA clones from the mats suggests that this microbial community is a unique consortium,
where the energy flow is related to hydrogen of hydrothermal origin, while mass growth of primary produces results from utilization
of sulfide formed by sulfate-and sulfur-reducing microorganisms.
Key wordsLost City hydrothermal field-microbial diversity-sulfate-reducing bacteria-16S rRNA-
dsrAB
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Desulfotomaculum
Microbiology 04/2012; 79(1):96-105. · 3.06 Impact Factor
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ABSTRACT: Fractionation of stable carbon isotopes 12C and 13C by three pure cultures of photoautotrophic purple sulfur bacteria (Ectothiorhodospira shaposhnikovii, Lamprocystis purpureus, and Thiocapsa sp.) (PSB) and the green sulfur bacterium Prosthecochloris sp. (GSB) was investigated in 13–15-day experiments. The cultivation was carried out in a luminostat (2000 lx) on mineral
media with 1–1.5 g/l NaHCO3 (inoculum) with the subsequent transfer to the medium with up to 10 g/l NaHCO3. For PSB, the difference in the quantitative characteristics of the isotopic composition of suspended carbon (including bacterial
cells) and mineral carbon of the medium (Δ13C = δ13Csubstrate − δ13Cbiomass) changed from 15.0 to 34.3‰. For GSB, the range of Δ13C changes was significantly less (18.3–22.7‰). These data suggested the possibility of a pool of soluble mineral carbon in
PSB cells. The pool of intracellular mineral carbon was calculated; depending on the PSB species and growth stage, it varied
from 0 to 68% of the total cell carbon. The α coefficients reflecting the carbon isotope fractionation by PSB and GBS and
calculated from the changes of the bicarbonate carbon isotopic composition in the medium depending on its consumption were
1.029 ± 0.003 and 1.019 ± 0.001, respectively. These α values did not depend on the growth rate. CO2 fixation on ribulose-bisphosphate was shown to be the major factor determining the carbon isotope fractionation by PSB; at
the stage of CO2 penetration into the cell, fractionation was insignificant. In GSB, fractionation occurred mostly at CO2 penetration into the cell, while it was insignificant at the stage of carbon dioxide fixation in the reverse TCA cycle. Analysis
of the isotopic data of the photosynthesis by PSB and GSB in meromictic lakes also revealed that in PSB-dominated natural
communities suspended organic matter was more enriched with light 13C (Δ13C = 23.4−24.6‰) than in the communities with more active GSB (Δ13C = 10.2−14.0‰)
Microbiology 04/2012; 78(6):757-768. · 3.06 Impact Factor
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ABSTRACT: In order to assess the phylogenetic diversity of the endosymbiotic microbial community of the gills of marine bivalve Bathymodiolus azoricus, total DNA was extracted from the gills. The PCR fragments corresponding to the genes encoding 16S rRNA, ribulose-bisphosphate
carboxylase (cbbL), and particulate methane monooxygenase (pmoA) were amplified, cloned, and sequenced. For the 16S rDNA genes, only one phylotype was revealed; it belonged to the cluster
of thiotrophic mytilid’s symbionts within the Gammaproteobacteria. For the RuBisCO genes, two phylotypes were found, both belonging to Gammaproteobacteria. One of them was closely related to the previously known mytilid symbiont, the other, to a pogonophore symbiont, presumably
a methanotrophic bacterium. One phylotype of particulate methane oxygenase genes was also revealed; this finding indicated
the presence of a methanotrophic symbiont. Phylogenetic analysis of the pmoA placed this endosymbiont within the Gammaproteobacteria, in a cluster including the methanotrophic bacterial genus Methylobacter and other methanotrophic Bathymodiolus gill symbionts. These results provide evidence for the existence of two types of endosymbionts (thioautotrophic and methanotrophic)
in the gills of B. azoricus and demonstrate that, apart from the phylogenetic analysis of 16S rRNA genes, parallel analysis of functional genes is essential.
Microbiology 04/2012; 75(6):694-701. · 3.06 Impact Factor
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ABSTRACT: Chemical and key microbiological processes (assimilation of carbon dioxide, oxidation and formation of methane, and sulfate
reduction) occurring at the aerobic-anaerobic interface in the deep-water zone of the Black Sea were investigated. Measurements
were taken at depths from 90 to 300 m at intervals of 5–10 m. The integral rate of the dark assimilation of carbon dioxide
varied from 120 to 207 mg C/(m2 day) with a maximum at the boundary of cyclonic currents. The organic matter (OM) formed from methane comprised less than
5% of the OM formed from carbon dioxide. A comparison between the rates of methane oxidation and methane production suggests
that methane that is oxidized at depths from 100 to 300 m was formed in deeper water horizons. The maximum rate of sulfate
reduction (1230 mg S/(m2 day)) was observed in the western halistatic region, and the minimum rate (490 mg S/(m2 day)), in the eastern halistatic region. The average rate of hydrogen sulfide production measured at three deep-sea stations
amounted to 755 mg S/(m2 day), or 276 g S/(m2 year).
Microbiology 04/2012; 69(4):436-448. · 3.06 Impact Factor
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Microbiology 04/2012; 78(6):798-801. · 3.06 Impact Factor
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ABSTRACT: Biogeochemical cycle of methane in the Barents Sea was studied using isotope geochemistry to determine the rates of microbial
methane oxidation. It was established that microbiological processes (glucose consumption, 14CO2 assimilation, sulfate reduction, and slow methane oxidation) in oxidized surface and weakly reduced sediments are marked
by only insignificant change in SO42− concentration and absence of notable growth of total alkalinity and N/NH4 downward the sediment core. Microbial methane productivity was 0.111 × 106 mol day−1. Taking into account the volume of water column, microbial methane consumption therein can be as much as 1.8 × 106 mol day−1.
Lithology and Mineral Resources 04/2012; 43(5):405-428. · 0.38 Impact Factor
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ABSTRACT: Fluorescent in situ hybridization (FISH) was used to analyze the abundance and phylogenetic composition of sulfate-reducing
bacteria in the aerobic waters and in the oxic/anoxic transitional zone (chemocline) of the Black Sea, where biogenic formation
of reduced sulfur compounds was detected by radioisotope techniques. Numerous sulfate-reducing bacteria of the genera Desulfotomaculum (30.5% of detected bacterial cells), Desulfovibrio (29.6%), and Desulfobacter (6.7%) were revealed in the aerobic zone at a depth of 30 m, while Desulfomicrobium-related bacteria (33.5%) were prevalent in the upper chemocline waters at 150-m depth. Active cells of sulfate-reducing bacteria
were much more abundant in the samples collected in summer than in the winter samples from the deep-sea zone. The presence
of physiologically active sulfate reducers in oxic and chemocline waters of the Black Sea correlates with the hydrochemical
data on the presence of reduced sulfur compounds in the aerobic water column.
Keywordsmeromictic basin–Black Sea–aerobic waters–chemocline–sulfate-reducing bacteria–fluorescent in situ hybridization
Microbiology 04/2012; 80(1):108-116. · 3.06 Impact Factor
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ABSTRACT: The production and oxidation of methane and diversity of culturable aerobic methanotrophic bacteria in the water column and
upper sediments of the meromictic oligotrophic Lake Gek-Gel (Azerbaijan) were studied by radioisotope, molecular, and microbiological
techniques. The rate of methane oxidation was low in the aerobic mixolimnion, increased in the chemocline, and peaked at the
depth where oxygen was detected in the water column. Aerobic methanotrophic bacteria of type II belonging to the genus Methylocystis were identified in enrichment cultures obtained from the chemocline. Methane oxidation in the anaerobic water of the monimolimnion
was much more intense than in the aerobic zone. However, below 29–30 m methane concentration increased and reached 68 μM at
the bottom. The highest rate of methane oxidation under anaerobic conditions was revealed in the upper layer of bottom sediments.
The rate of methane oxidation significantly exceeding that of methane production suggests a deep source of methane in this
lake.
Key wordsmeromictic oligotrophic Lake Gek-Gel-methanogenesis-methane oxidation-methanotrophic bacteria
Microbiology 04/2012; 79(2):247-252. · 3.06 Impact Factor
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ABSTRACT: The rates of photosynthesis and dark CO2 fixation were determined in 12 soda lakes of the Kulunda steppe. Characterization of the phototrophic communities was given,
and the cell numbers of anoxygenic phototrophic bacteria (APB) were determined. The photosynthetic production in different
lakes was substantially different, constituting from 0.01 to 1.32 g C m−2 day−1. The main part of carbon dioxide was assimilated in the process of oxygenic photosynthesis. Anoxygenic photosynthesis was
recorded only in 5 of the 12 lakes studied. Its values varied between 0.06 and 0.42 g C m−2 day−1, constituting from 8 to 34% of the total photosynthetic activity. Anoxygenic photosynthesis was revealed in the lakes where
the number of APB reached 107–109 CFU cm−3. Dark CO2 fixation constituted 0.01–0.15 g C m−2 day−1. Positive correlation was observed between the primary production value and water alkalinity. No relationship between productivity
and water mineralization was revealed in the 30–200 g l−1 range, whereas an increase in salinity above 200 g l−1 suppressed the photosynthetic activity. The mechanisms of influence of the environmental factors on the rate of photosynthesis
are discussed.
Microbiology 04/2012; 78(5):643-649. · 3.06 Impact Factor
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ABSTRACT: The rate of CO conversion by a pure culture of a thermophilic CO-oxidizing, H2-producing bacterium Carboxydocella sp. strain 1503 was determined by the radioisotopic method. The overall daily uptake of 14CO by the bacterium was estimated at 38–56 μmol CO per 1 ml of the culture. A radioisotopic method was developed to separate
and quantitatively determine the products of anaerobic CO conversion by microbial communities in hot springs. The new method
was first tested on the microbial community from a sample obtained from a hot spring in Kamchatka. The potential rate of CO
conversion by the anaerobic microbial community was found to be 40.75 nmol CO/cm3 sediment per day. 85% of the utilized 14CO was oxidized to carbon dioxide; 14.5% was incorporated into dissolved organic matter, including 0.2% that went into volatile
fatty acids; 0.5% was used for cell biomass production; and only just over 0.001% was converted to methane.
Microbiology 04/2012; 76(5):523-529. · 3.06 Impact Factor
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ABSTRACT: The isotopic composition of particulate organic carbon (POC) from the Black Sea deep-water zone was studied during a Russian-Swiss
expedition in May 1998. POC from the upper part of the hydrogen sulfide zone (the C-layer) was found to be considerably enriched
with the12C isotope, as compared to the POC of the oxycline and anaerobic zone. In the C-layer waters, the concurrent presence of dissolved
oxygen and hydrogen sulfide and an increased rate of dark CO2 fixation were recorded, suggesting that the change in the POC isotopic composition occurs at the expense of newly formed
isotopically light organic matter of the biomass of autotrophic bacteria involved in the sulfur cycle. In the anaerobic waters
below the C-layer, the organic matter of the biomass of autotrophs is consumed by the community of heterotrophic microorganisms;
this results in weighting of the POC isotopic composition. Analysis of the data obtained and data available in the literature
allows an inference to be made about the considerable seasonable variability of the POC δ13C value, which depends on the ratio of terrigenic and planktonogenic components in the particulate organic matter.
Microbiology 04/2012; 69(4):449-459. · 3.06 Impact Factor
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ABSTRACT: Mass-spectrometric investigation of carbon isotope composition (δ13C) was carried out for suspended organic matter and dissolved mineral compounds for the water column of some meromictic water
bodies differing in salinity and trophic state. As a rule, a more pronounced carbon isotope fractionation (resulting from
the metabolism of phytoplankton and anoxygenic phototrophic bacteria) was revealed in the zones of enhanced oxygenic and anoxygenic
photosynthesis. Carbon isotope fractionation at the border between oxidized and reduced waters depends both on the activity
of microbial communities and on the dominant species of phototrophic microorganisms. Analysis of the distribution profiles
of the isotopic composition of suspended organic matter and dissolved mineral carbon revealed active mineralization of the
organic matter newly formed via anoxygenic photosynthesis in the monimolimnion by microbial communities, resulting in the
release of isotopically light carbon dioxide. Mineral carbon in the anaerobic zones of highly productive meromictic water
bodies is therefore enriched with the light 12C isotope.
Microbiology 11/2008; 77(6):751-759. · 3.06 Impact Factor
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ABSTRACT: The anoxygenic phototrophic bacterial community of the high-altitude meromictic Lake Gek-Gel (Azerbaijan) was investigated
in September 2003. The highest concentration of bacteriochlorophyll e (48 μg/l) was detected at a depth of 30 m; the peak of bacteriochlorophyll a (4.5 μg/l) occurred at 29 m. Phylogenetic analysis revealed that brown-colored green sulfur bacteria Chlorobium phaeobacteroides predominated in the lake. Nonsulfur purple bacteria phylogenetically close to Blastochloris sulfoviridis were found in insignificant amounts; these organisms have not been previously reported in Lake Gek-Gel.
Microbiology 09/2008; 77(5):602-609. · 3.06 Impact Factor
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ABSTRACT: Comprehensive microbiological and biogeochemical investigation of a pockmark within one of the sites of gas-saturated sediments
in the Gdansk depression, Baltic Sea was carried out during the 87th voyage of the Professor Shtokman research vessel. Methane content in the near-bottom water and in the underlying sediments indicates stable methane flow from
the sediment into the water. In the 10-m water layer above the pockmark, apart from methane anomalies, elevated numbers of
microorganisms and enhanced rates of dark CO2 fixation (up to 1.15 µmol C/(l day)) and methane oxidation (up to 2.14 nmol CH4/(l day)) were revealed. Lightened isotopic composition of suspended organic matter also indicates high activity of the near-bottom
microbial community. Compared to the background stations, methane content in pockmark sediments increased sharply from the
surface to 40–60 ml/dm3 in the 20–30 cm horizon. High rates of bacterial sulfate reduction (SR) were detected throughout the core (0–40 cm); the
maximum of 74 µmol S/(dm3 day) was located in subsurface horizons (15–20 cm). The highest rates of anaerobic methane oxidation (AMO), up to 80 µmol/dm3 day), were detected in the same horizon. Good coincidence of the AMO and SR profiles with stoichiometry close to 1: 1 is
evidence in favor of a close relation between these processes performed by a consortium of methanotrophic archaea and sulfate-reducing
bacteria. Methane isotopic composition in subsurface sediments of the pockmark (from −53.0 to −56.5‰) does not rule out the
presence of methane other than the biogenic methane from the deep horizons of the sedimentary cover.
Microbiology 09/2008; 77(5):579-586. · 3.06 Impact Factor
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ABSTRACT: The possibility of measuring the rates of light and dark CO2 assimilation using 13C carbonate was demonstrated on Lake Kichier (Marii El). The application of methods utilizing the stable 13C and the radioactive 14C isotopes resulted in comparable values of the rates of light and dark CO2 fixation. Due to its absolute environmental safety, the method with 13C mineral carbon can be recommended as an alternative to radioisotope methods for qualitative measurements of CO2 fixation rates in aquatic ecosystems.
Microbiology 03/2008; 77(2):224-227. · 3.06 Impact Factor
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ABSTRACT: The anoxygenic phototrophic bacterial community of the brackish meromictic Lake Shira (Khakassia) was investigated in August
2001, July 2002, and February–March 2003. In all the periods of investigation, the prevailing microorganisms were purple sulfur
bacteria similar to Lamprocystis purpurea in morphology and pigment composition. Their highest number (3 × 105 cells/ml) was recorded in July 2002 at the depth of 15 m. According to 16S rRNA gene analysis, the strain of purple sulfur
bacteria isolated in 2001 and designated ShAm01 exhibited 98.6% similarity to the type strain of Thiocapsa roseopersicina and 97.1–94.4% similarity to the type strains of Tca. pendens, Tca. litoralis, and Tca. rosea. The minor microorganisms of the anoxygenic phototrophic bacterial community within the period of investigation were nonsulfur
purple bacteria phylogenetically close to Rhodovulum strictum (98.3% similarity, strain ShRb01), Ahrensia kielensis (of 93.9% similarity, strain ShRb02), Rhodomicrobium vannieli (of 99.7% similarity, strain ShRmc01), and green sulfur bacteria, phylogenetically close to Chlorobium limicola (of 98.7% similarity, strain ShCl03).
Microbiology 07/2007; 76(4):469-479. · 3.06 Impact Factor
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ABSTRACT: Seasonal studies of the anoxygenic phototrophic bacterial community of the water column of the saline eutrophic meromictic
Lake Shunet (Khakassia) were performed in 2002 (June) and 2003 (February–March and August). From the redox zone down, the
lake water was of dark green color. Green sulfur bacteria predominated in every season. The maximum number of green sulfur
bacteria was 107 cells/ml in summer and 106 cells/ml in winter. A multi-syringe stratification sampler was applied for the study of the fine vertical distribution of
phototrophs in August 2003; the sampling was performed every 5 cm. A 5-cm-thick pink-colored water layer inhabited by purple
sulfur bacteria was shown to be located above the layer of green bacteria. The species composition and ratio of purple bacterial
species depended on the sampling depth and on the season. In summer, the number of purple sulfur bacteria in the layer of
pink water was 1.6 × 108 cells/ml. Their number in winter was 3 × 105 cells/ml. In the upper oxygen-containing layer of the chemocline the cells of purple nonsulfur bacteria were detected in
summer. The maximum number of nonsulfur purple bacteria, 5 × 102 cells/ml, was recorded in August 2003. According to the results of the phylogenetic analysis of pure cultures of the isolated
phototrophic bacteria, which were based on 16S rDNA sequencing, green sulfur bacteria were close to Prosthecochloris vibrioformis, purple sulfur bacteria, to Thiocapsa and Halochromatium species, and purple nonsulfur bacteria, to Rhodovulum euryhalinum and Pinkicyclus mahoneyensis.
Microbiology 05/2007; 76(3):368-379. · 3.06 Impact Factor
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ABSTRACT: Study of biogeochemical processes in water and sediments of the Chukchi Sea in August 2004 revealed atypical maximums of the
concentration of biogenic elements (N, P, and Si) and the rate of microbial sulfate reduction in the surface layer (0–3 cm)
of marine sediments. The C: N: P ratio in the organic matter (OM) of this layer does not fit the Redfield-Richards stoichiometric
model. Specific features of biogeochemical processes in sea are likely related to the complex dynamics of water, high primary
productivity (110–1400 mg C/(m2 day)), low depth of basin (<50 m in 60% of the water area), reduced food chain due to low population of zooplankton, high
density of zoobenthos (up to 4230 g m−2), and high activity of microbial processes. Drastic decrease in the concentration of biogenic elements, iodine, total alkalinity
(Alk), and population of microorganisms beneath the 0–3 cm layer testify to a large-scale OM decay at the water-seafloor barrier.
Our original experimental data support the high annual rate of OM mineralization at the bottom of the Chukchi Sea.
Lithology and Mineral Resources 01/2007; 42(3):221-239. · 0.38 Impact Factor
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Microbiology 02/2006; 75(2):237-239. · 3.06 Impact Factor
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ABSTRACT: The biogeochemical and molecular biological study of the chemocline and sediments of saline meromictic lakes Shira and Shunet
(Khakasia, Russia) was performed. A marked increase in the rates of sulfate reduction and methanogenesis was revealed at the
medium depths of the chemocline. The rates of these processes in the bottom sediments decreased with depth. The numbers of
the members of domains Bacteria, Archaea, and of sulfate-reducing bacteria (SRB) were determined by fluorescence in situ hybridization with rRNA specific oligonucleotide
probes labeled with horseradish peroxidase and subsequent tyramide signal amplification. In the chemocline, both the total
microbial numbers and those of Bacteria were shown to increase with depth. The archaea and SRB were present in almost equal numbers. In the lake sediments, a drastic
decrease in microbial numbers with depth was revealed. SRB were found to prevail in the upper sediment layer and archaea in
the lower one. This finding correlated with the measured rates of sulfate reduction and methanogenesis.
Microbiology 01/2006; 75(6):720-726. · 3.06 Impact Factor
