EXPERIMENTAL TRANSFORMATION OF ORGANIC MATTER BY THE MICROBIAL COMMUNITY FROM THE BOTTOM SEDIMENTS OF AKADEMICHESKY RIDGE (LAKE BAIKAL)
O.N. Pavlova1, S.V. Bukin1, E.A. Kostyreva2, V.I. Moskvin2,3, A.Yu. Manakov4, I.V. Morozov5,3, Yu.P. Galachyants1, A.V. Khabuev1, T.I. Zemskaya1
1Limnological Institute, Siberian Branch of Russian Academy of Sciences, ul. Ulan-Batorskaya 3, Irkutsk, 664033, Russia
2A.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of Russian Academy of Sciences, pr. Akademika Koptuga 3, Novosibirsk, 630090, Russia
3Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia
4A.V. Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences, pr. Akademika Lavrent’eva 3, Novosibirsk, 630090, Russia
5Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Lavrent’eva 8, Novosibirsk, 630090, Russia
Keywords: deep biosphere, transformation of organic matter, microbial community, temperature and pressure conditions, Lake Baikal
Abstract
We discuss the results of a model experiment on cultivation of the microbial community from the area of the Khoboy mud volcano (Akademichesky Ridge) conducted under conditions typical of the hydrocarbon generation zone (80 °C, 5 MPa). The cultivation under conditions of biomass enrichment with the Baikal diatom Synedra acus changed the composition of organic matter. The transformation degree of organic matter in the sediment after the experiment was 16%, whereas the concentration of phenanthrenes relative to methyl-substituted homologues, including retene, decreased, and the concentration of dibenzothiophenes relative to normal alkanes increased. We have identified tri- and monoaromatic steroids, including 17-dismethyl, 23-methyl monoaromatic steroids C27. An increase in the concentration of tri- and monoaromatic steroids in the sediments after the experiment might indicate that the biomass of the Baikal diatom S. acus was destructed, which led to an increase in the steroid concentration. In the control (sterile) sediment, we detected no changes in the composition of organic matter. Representatives of various taxa capable of surviving in anaerobic thermophilic conditions have been identified in the microbial community by molecular genetic methods. Their presence in the surface sediments might be due to the inflow of deep-seated mineralized fluids and breccia from deep-seated sedimentary rocks.
DOI: 10.15372/RGG2019099
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