Heterotrophic bicarbonate assimilation is the main process of de novo organic carbon synthesis in hadal zone of the Hellenic Trench, the deepest part of Mediterranean Sea. Issue 6 (28th July 2014)

• Record Type: Journal Article
• Authors: Yakimov, Michail M.; La Cono, Violetta; Smedile, Francesco; Crisafi, Francesca; Arcadi, Erika; Leonardi, Marcella; Decembrini, Franco; Catalfamo, Maurizio; Bargiela, Rafael; Ferrer, Manuel; Golyshin, Peter N.; Giuliano, Laura
• Is Part Of: Environmental microbiology reports. Volume 6:Issue 6(2014)
• Page Start: 709
• Page End: 722
• Publication Date: 2014-07-28
• Subjects: Microbial ecology -- Periodicals; Environmental Microbiology -- Periodicals; Electronic journals; 579.17
• DOI: 10.1111/1758-2229.12192
• Languages: English
• ISSNs: 1758-2229

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>Ammonium‐oxidizing chemoautotrophic members of <italic>T</italic><italic>haumarchaea</italic> are proposed to be the key players in the assimilation of bicarbonate in the dark (ABD). However, this process may also involve heterotrophic metabolic pathways, such as fixation of carbon dioxide (CO<sub>2</sub>) via various anaplerotic reactions. We collected samples from the depth of 4900 m at the Matapan‐Vavilov Deep (MVD) station (Hellenic Trench, Eastern Mediterranean) and used the multiphasic approach to study the ABD mediators in this deep‐sea ecosystem. At this depth, our analysis indicated the occurrence of actively CO<sub>2</sub>‐fixing heterotrophic microbial assemblages dominated by <italic>G</italic><italic>ammaproteobacteria</italic> with virtually no <italic>T</italic><italic>haumarchaea</italic> present. [<sup>14</sup>C]‐bicarbonate incorporation experiments combined with shotgun [<sup>14</sup>C]‐proteomic analysis identified a series of proteins of gammaproteobacterial origin. More than quarter of them were closely related with <italic>A</italic><italic>lteromonas macleodii</italic> 'deep ecotype' AltDE, the predominant organism in the microbial community of MVD. The present study demonstrated that in the aphotic/hadal zone of the Mediterranean Sea, the assimilation of bicarbonate is associated with both chemolithoauto‐ and heterotrophic ABD. In some deep‐sea areas, the latter may predominantly contribute to the <italic>de novo</italic> synthesis of organic carbon which points at the important and yet underestimated role heterotrophic bacterial populations can play the in global carbon cycle/sink in the ocean interior.</p> </abstract>