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| DEPARTMENT OF MICROBIAL COMMUNITIES LABORATORY
OF HYPERTHERMOPHILIC Head of Laboratory Telephone: +7 (495) 135-44-58
Staff
Doctors of Biological Sciences 1 Major fields of investigation:
The Laboratory was founded in May, 1996, as a part of the Departments of Microbial Communities (Head Academician Georgy A. Zavarzin). The Laboratory researchers investigated various natural ecotopes of thermophilic prokaryotes: terrestrial hydrotherms at Kamchatka, Kuriles, Yellowstone National Park, deep-water hydrotherms in the Pacific and Atlantic Oceans, high-temperature oil deposits of Western Siberia. Lithotrophic and organotrophic thermophilic bacteria and archaea, including hyperthermophiles, whose optimim growth temperature is > 100°C, have been the subject of much experimentation. A large number of new taxons of thermophilic prokaryotes were isolated and described, such as: the new order Nautiliales, family Nautiliaceae, genera Desulfurella, Hippea, Nautilia, Oceanithermus, Vulcanithermus, Caldithrix, Thermovenabulum, Tepidibacter, Thermosinus, Carboxydocella, and Thermoincola, and a large amount of new species. Hydrogen-utilizing lithotrophs and microorganisms with various types of anaerobic respiration (sulfur, nitrate, and iron reducers) received primary attention. Some new isolates (Nautiliales ord. nov., Caldithrix gen. nov.) are the first cultured representatives of new phylogenetic branches that were previously represented only in clone libraries obtained from thermal habitat. A novel phylogenetic group of microorganisms, thermophilic hydrogen-producing carboxidotrophs, has been described. It was shown that a wide range of thermophilic prokaryotes belonging to various phylogenetic positions, including hyperthermophilic archaea of the genus Thermococcus, are capable of growth at the expense of anaerobic CO oxidation with simultaneous hydrogen production from water. Our scientists are investigating the ability of thermophilic prokaryotes to reduce toxic metals, metalloids, and radionuclides. They were the first to determine the ability of thermophilic prokaryotes to reduce chrome and uranium during their growth. Bacillus thermoamylovorans SKC1 - a facultatively-anaerobic thermophilic bacterium - reducing 0.3 mM of chrome during anaerobic growth was isolated. The reduction of U(VI) to U(IV) by cell suspensions and growing cultures of Thermoterrabacterium ferrireducens has been investigated. For example, a cell suspension (172 mkg of protein) has reduced 1.75 M of uranium during 24 h of incubation. As this takes place, uranium is completely expelled from the solution as an insoluble precipitate. This phenomenon makes it possible to use this process for cleansing purposes. The dissimilatory reduction of selenate and selenite to elemental selenium by thermophilic and hyperthermophilic archaea and bacteria was described for the first time. The Laboratory's research achievements include purification and description of the following thermostable enzymes produced by novel thermophilic prokaryotes: phosphatase from the hyperthermophilic archaeabacterium Thermococcus pacificu, DNA polymerase from the hyperthermophilic archaebacterium Thermococcus ShAM , iron-reductase from the thermophilic bacterium Thermoterrabacterium ferrireducens. Reasearchers are investigating thermophilic prokaryotes with hydrolytic activity that produce thermostable proteinases: keratinases decomposing alpha- and beta- keratins, cellulase, and agarases. The Laboratory team members are developing molecular-biological methods for analyzing thermophilic microbial communities: PCR with 16S rRNA-targeted primers, hybridization with 16S rRNA-specific oligonucleotide probes. They have also designed a computer program that allows for selecting PCR primers and oligonucleotide probes with various levels of specificity. The program's algorithm is based on the use of the oligonucleotide vocabularies produced by the program itself. This speeds up the search process in comparison with direct selection or multiple alignments. The program takes into account such parameters as the number of mismatches for each probe or primer with non-targeted sequences, melting point of a potential duplex, or the tendency of oligonucleotides to form loops and dimers. A system of primers enabling express-detection of archaea of the Crenarchaeota Kingdom and, more specifically, of the order Thermococcales has been developed. This system made it easy to identify a number of new isolates of Thermococcales with new phenotypical features. New hyperthermophilic archaea (Crenarchaeota) were found in the anthropogenic habitat - a thermophilic methane-tank. Analysis of the 16S rRNA nucleotide sequence has shown that this new species belongs to the genus Sulfophobococcus. The only known member of this species was isolated from Icelandic hydrotherms. Another representative of Crenarchaeota was detected in the sediments of a hot spring near Baikal Lake with this system of primers. The closest relative of this organism is a reputedly uncultivated microorganisms presented in the clone library from a Yellowstone hot spring. A preliminary phenotypic characterization of this new organism was done by the monitoring of enrichment cultures with molecular methods. This microorganism has been shown to be an organotroph, obligate aerobe, moderate thermophile and alkalophile. Some organisms with new biotechnologically important features were identified by the chemoluminescent 16S rRNA-targeted oligonucleotide probes specific to the thermophilic bacteria of the genus Thermoanaerobacter and hyperthermophilic archaea of the genus Desulfurococcus, producers of new thermostable enzymes (agarase and cellulase), and CO-consuming microorganisms. A system consisting of 57 oligonucleotide probes (16S rRNA) has been designed; it allow one to carry out express analysis of thermophilic microbial communities. The Laboratory team together with specialists from the Engelhardt Institute of Molecular Biology has designed a chip which allows studying biodiversity of thermophilic prokaryotes in natural ecosystems. This microchip was used during the investigation of thermophilic microbial communities in a high-temperature oil deposit (in cooperation with the Laboratory of Oil Microbiology, Winogradsky Institute of Microbiology RAS). Cultural, radioisotope, and molecular-biological methods were simultaneously used. This provided strong evidence for the existence of an indigenous hyperthermophilic microbial community at a depth of 2500-3000 m (85°C). The new species of hyperthermophilic archaea, Thermococcus sibiricus, was isolated from the same habitat. The Laboratory researchers and scientists working
at the Laboratory of
Microbiology and Biogeochemistry of Water Bodies investigated
the basic microbiological processes in terrestrial and marine hydrotherms
by radioactive methods: lithotrophic and aceticlastic methanogenesis,
sulfate reduction, primary production and mineralization of organic
matter, as well as the impact of potential electron donors and acceptors
on these processes. Not only do these data allow us to judge the
rates of the above processes, but also point to the existence of
new groups of microorganisms which are still uncultivated, such
as high temperature acetoclastic methanogens.
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