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ORIGINAL RESEARCH article

Front. Microbiol.
Sec. Extreme Microbiology
Volume 15 - 2024 | doi: 10.3389/fmicb.2024.1441865
This article is part of the Research Topic Deep Subsurface Microbiology and Energetics View all 4 articles

Novel thermophilic genera Geochorda gen. nov. and Carboxydochorda gen. nov. from deep terrestrial subsurface reveal ecophysiological diversity in the class Limnochordia

Provisionally accepted
Olga V. Karnachuk Olga V. Karnachuk 1*Anastasiya P. Lukina Anastasiya P. Lukina 1Marat R. Avakyan Marat R. Avakyan 1Vitaly V. Kadnikov Vitaly V. Kadnikov 2Shahjahon Begmatov Shahjahon Begmatov 2Alexey V. Beletsky Alexey V. Beletsky 2Ksenia G. Vlasova Ksenia G. Vlasova 1Viktoria A. Shcherbakova Viktoria A. Shcherbakova 3Andrei A. Novikov Andrei A. Novikov 4Andrey V. Mardanov Andrey V. Mardanov 2Nikolai V. Ravin Nikolai V. Ravin 2
  • 1 Tomsk State University, Tomsk, Russia
  • 2 Institute of Bioengineering, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Moscow Oblast, Russia
  • 3 G. K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Pushchino, Russia
  • 4 Gubkin Russian State University of Oil and Gas, Moscow, Moscow Oblast, Russia

The final, formatted version of the article will be published soon.

    The class Limnochordia harbors a single cultivated member, the mesophilic Limnochorda pilosa, isolated from a meromictic lake, and despite numerous molecular signatures reported for various ecosystems, the ecophysiological versatility of this deeply branched lineage of Firmicutes (Bacillota) remains poorly understood. The goal of the present study was to use targeted cultivation based on metagenome-assembled genome from a deep terrestrial aquifer in Western Siberia to isolate two new thermophilic members of the class. Isolates described as Geochorda subterranea gen. nov. sp. nov. and Carboxydochorda subterranea gen. nov. sp. nov. within the Geochordaceae fam. nov. were capable of both anaerobic and aerobic respiration with fumarate and O2, respectively, using simple sugars as electron donors. Cultivated Geochordaceae have demonstrated fermentative growth and degradation of polymers including starch, maltose, maltodextrin, xylan, and chitin. Carboxydotrophic C. subterranea sp. nov. exhibited autotrophic growth via the Calvin-Benson-Bassham cycle with CO, H2 and formate as electron donors and O2 as electron acceptor, adding metabolic flexibility to the bacterium in the nutrient-depleted "deep biosphere" and supporting the possibility of aerobic metabolism in the deep subsurface. The broad physiological potential deciphered from physiological experiments and comparative genomic data explains the widespread distribution of uncultivated members of the class Limnochordia in various ecosystems, where they can oxidize complex organic substrates through both, aerobic and anaerobic respiration, as well as pursue a chemolithotrophic lifestyle through oxidation H2 or CO.

    Keywords: deep terrestrial subsurface, Limnochordia, thermophiles, carboxydotrophs, aerobic respiration, didermic cell wall

    Received: 31 May 2024; Accepted: 27 Aug 2024.

    Copyright: © 2024 Karnachuk, Lukina, Avakyan, Kadnikov, Begmatov, Beletsky, Vlasova, Shcherbakova, Novikov, Mardanov and Ravin. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Olga V. Karnachuk, Tomsk State University, Tomsk, Russia

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