Glucose transport into the extremely halophilic archaebacteria

Penetration of glucose into cells of several extremely halophilic archaebacteria of the Halobacterium and Haloferax genera (Halobacterium saccharovorum and Halobacterium salinarium, Haloferax volcanii and Haloferax mediterranei) has been studied. Some characteristics of transport systems of carbohydrate-utilizing halobacteria Halobacterium saccharovorum, Haloferax mediterranei and Haloferax volcanii (pH and temperature optima, stereospecificity, kinetic parameters) have been determined. Inability of H. salinarium cells for active glucose transport has been shown. The dependence of glucose transport on the Na⁺ ions gradient (on the whole cells and membrane vesicles) has been demonstrated. Cells or membrane vesicles of carbohydrate-utilizing halobacteria grown in media containing this sugar indicated the activation of glucose transport, whereas cells grown in media without sugars did not. This fact has allowed us to conclude that corresponding transport systems are inducible.     

Comparative Study of Methanogenic Pathways in the Sediments of Thermokarst and Polygenetic Yamal Lakes

Microbiology - Comparative study of methanogen diversity and potential activity of different methanogenic pathways in the sediments of young thermokarst and mature polygenetic Yamal lakes was...     

Erratum to: On the Possibility of Aerobic Methane Production by Pelagic Microbial Communities of the Laptev Sea

Microbiology - An Erratum to this paper has been published: https://doi.org/10.1134/S0026261721110011     

On the Possibility of Aerobic Methane Production by Pelagic Microbial Communities of the Laptev Sea

Microbiology - The taxonomic diversity and metabolic activity of microbial communities in the Laptev Sea water column above and outside the methane seep field were studied. The concentrations of...     

Thermotolerant Methanotrophic Bacteria from Sediments of the River Chernaya,Crimea, and Assessment of Their Growth Characteristics

Microbiology - The technology of single-cell protein production from natural gas is based on using thermotolerant methanotrophic bacteria with high growth rates on methane. So far, the spectrum of...     

Prokaryotic Communities in Saline Soils of the Lake Elton Area in a Soil Catena along the Khara River

Microbiology - Analysis of the taxonomic structure of prokaryotic microbial complexes of the saline soils in the Lake Elton area and their comparative characteristics were carried out for a soil...     

Identification of Aerobic Methane-Oxidizing Bacteria in Coastal Sediments of the Crimean Peninsula

Microbiology - Methane oxidation rates and diversity of methane-oxidizing microorganisms in the upper sediment layers of the Crimean Peninsula coastal regions (Black Sea) were investigated....     

Sulfate reduction, methanogenesis, and methane oxidation in the upper sediments of the Vistula and Curonian Lagoons, Baltic Sea

Microbiological, biogeochemical, and isotope geochemical investigations of the upper sediments of the Vistula and Curonian lagoons, Baltic Sea, were carried out. High content of organic matter in the sediments was responsible for the high numbers (over 10¹⁰ cells cm^?3) and activity of heterotrophic microorganisms. The calculated integral rates of dark CO₂ assimilation for the upper 30 cm of the sediments varied 12.5 to 38.8 mmol m^?2 day^?1 and were somewhat higher in the Curonian Lagoon than in the Vistula Lagoon. Integral rates of sulfate reduction were higher in the more saline Vistula Lagoon. Rapid consumption of sulfates of the pore water resulted in intensified methanogenesis, with significantly higher rates detected in the silts of the Curonian Lagoon. High rates of methanogenesis in the Curonian Lagoon correlated with higher methane levels in its upper sediments and near-bottom water. The highest rates of methane oxidation were detected in the uppermost sediment horizons (oxidized or slightly reduced), which was an indication of the barrier role of aerobic methanotrophic bacteria. The calculated methane flows from the sediments into the water column were 0.45 and 0.007 mmol m^?2 day^?1 for the Vistula and Curonian Lagoons, respectively. Low methane flow from the sediments of the Curonian Lagoon resulted probably from the specific weather (wind) conditions during sampling. The near-stormy conditions in the Curonian Lagoon caused sediment detachment, resulting in methane release into the water column.     

Components of antioxidant systems in the cells of aerotolerant sulfate-reducing bacteria of the genus <Emphasis Type="Italic">Desulfovibrio</Emphasis> (strains A2 and TomC) isolated from metal mining waste

Two strains of sulfate-reducing bacteria of the genus Desulfovibrio (A2 and TomC) isolated from metal mining waste were able to grow on agar Postgate C nutrient medium under microaerobic conditions. Since their growth in liquid nutrient medium was just slightly affected by 1% O₂ (initial concentration in the gas phase) and 0.05–0.1 mM H₂O₂, these strains were relatively oxygen-tolerant. Only the presence of oxidants in high concentrations (5–10% О₂ or 0.3–1.0 mM H₂O₂) resulted in practically complete inhibition of their growth. Strain A2 was more resistant to oxidative stresses than strain TomC. Activities of the key enzymes of antioxidant defense—superoxide dismutase (SOD), catalase, and peroxidase—were revealed in the cell-free extracts of strain A2 grown under strict anaerobic conditions. While strain TomC was found to possess no peroxidase activity, its catalase activity was much higher than that of strain A2 (36 and 2 U/mg protein, respectively). SOD activity of both strains was almost the same (5 U/mg protein). Sublethal H₂O₂ doses (concentration of 0.05–0.15 mM and exposure for 45–240 min) resulted in a drastic increase of catalase activity, especially in strain A2. Sublethal О₂ doses (1–2% in the gas phase) had no significant effect on activities of the antioxidant enzymes of both strains. The cytochrome composition determined from the absolute absorption spectra of the whole cells of strains TomC and A2 revealed the presence of the c heme (438 and 831 pmol/mg protein) and the d heme (336 and 303 pmol/mg protein, respectively). The presence of the d heme indicated the presence of the bd heme–heme quinol oxidase, which together with the c heme may provide for the functioning of the electron transport segment of the antioxidant defensive system, which is responsible for aerotolerance of sulfate-reducing bacteria.     

Sulfate reduction and inorganic carbon assimilation in acidic thermal springs of the Kamchatka peninsula

Thermoacidophilic sulfate reduction, which remains a poorly studied process, was investigated in the present work. Radioisotope analysis with ³⁵S-labeled sulfate was used to determine the rates of dissimilatory sulfate reduction in acidic thermal springs of Kamchatka, Russia. Sulfate reduction rates were found to vary from 0.054 to 12.9 nmol SO₄/(cm³ day). The Oil Site spring (Uzon caldera, 60°C, pH 4.2) and Oreshek spring (Mutnovskii volcano, 91°C, pH 3.5) exhibited the highest activity of sulfate-reducing prokaryotes. Stable enrichment cultures reducing sulfate at pH and temperature values close to the environmental ones were obtained from these springs. Analysis of the 16S rRNA gene sequences revealed that a chemolithoautotrophic bacterium Thermodesulfobium sp. 3127-1 was responsible for sulfate reduction in the enrichment from the Oil Site spring. A chemoorganoheterotrophic archaeon Vulcanisaeta sp. 3102-1 (phylum Crenarchaeota) was identified in the enrichment from Oreshek spring. Thus, dissimilatory sulfate reduction under thermoacidophilic conditions was demonstrated and the agents responsible for this process were revealed.