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Ecophysiological Characteristics of the Mat-forming Bacterium Thioplocain Bottom Sediments of the Frolikha Bay, Northern Baikal

  • Zemskaya, T. I.1
  • Namsaraev, B. B.2
  • Dul'tseva, N. M.3
  • Khanaeva, T. A.1
  • Golobokova, L. P.1
  • Dubinina, G. A.3
  • Dulov, L. E.3
  • Wada, E.4
  • 1 Institute of Limnology, Siberian Division, Russian Academy of Sciences, ul. Lermontova 281, Irkutsk, 664033, Russia , Irkutsk
  • 2 Institute of General Biology, Siberian Division, Russian Academy of Sciences, Ulan-Ude , Ulan-Ude
  • 3 Institute of Microbiology, Russian Academy of Sciences, pr. 60-letiya Oktyabrya 7, k. 2, Moscow, 117811, Russia , Moscow
  • 4 University of Kyoto, Center for Environmental Studies, Japan
Published Article
Pleiades Publishing
Publication Date
May 01, 2001
DOI: 10.1023/A:1010463613498
Springer Nature


A colorless sulfur bacterium of the genus Thioploca, which forms bacterial mats, was studied in the region of underwater thermal vents (Frolikha Bay, northern Baikal). The organism occurs under microaerobic conditions in top sediment layers, and its biomass can amount to 65 mg of wet weight per 1 kg of silt. Individual filaments of the bacterium penetrate the anaerobic zone to the depth of 19 cm. Thioplocais distributed in a mosaic pattern over the bottom of the bay. Thioplocamats are typically found near vents that discharge low-temperature underground water. In the form of separate filaments, this bacterium is more widely distributed in the top sediment layer, particularly in sediments with a more active sulfate reduction. The bacteria from the deep-water and coastal areas of the bay have different morphology. Cells of Thioplocaare able to accumulate nitrate, and the coefficient of nitrate accumulation in wet bacterial mass in relation to the near-bottom water is 1.3 × 104, suggesting a similarity of metabolism with seawater species. A more lightweight isotopic composition of nitrogen in cell mass as compared to that of representatives of zoobenthos also indicates an active metabolism of nitrogen, apparently, in the process of nitrogen respiration. Comparison of the composition of stable isotopes of carbon in the biomass of representatives of different trophic levels, including Thioploca, found at a depth of 105 m indicates its planktonic origin, whereas, in the deeper bay region, the biomass of Thioplocaincorporates more of the light carbon originating from biogenic methane.

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