BUSCADOR RECOLECTA

Digital.CSIC. Repositorio Institucional del CSIC

oai:digital.csic.es:10261/341455

Deep-sea microbial communities are exposed to high-pressure conditions, which has a variable impact on prokaryotes depending on whether they are piezophilic (that is, pressure-loving), piezotolerant or piezosensitive. While it has been suggested that elevated pressures lead to higher community-level metabolic rates, the response of these deep-sea microbial communities to the high-pressure conditions of the deep sea is poorly understood. Based on microbial activity measurements in the major oceanic basins using an in situ microbial incubator, we show that the bulk heterotrophic activity of prokaryotic communities becomes increasingly inhibited at higher hydrostatic pressure. At 4,000 m depth, the bulk heterotrophic prokaryotic activity under in situ hydrostatic pressure was about one-third of that measured in the same community at atmospheric pressure conditions. In the bathypelagic zone-between 1,000 and 4,000 m depth-~85% of the prokaryotic community was piezotolerant and ~5% of the prokaryotic community was piezophilic. Despite piezosensitive-like prokaryotes comprising only ~10% (mainly members of Bacteroidetes, Alteromonas) of the deep-sea prokaryotic community, the more than 100-fold metabolic activity increase of these piezosensitive prokaryotes upon depressurization leads to high apparent bulk metabolic activity. Overall, the heterotrophic prokaryotic activity in the deep sea is likely to be substantially lower than hitherto assumed, with major impacts on the oceanic carbon cycling., Field experiments were conducted during the research cruises: MODUPLAN (CTM-2011-24008), RADPROF201508, RADPROF201808, RADCAN201808, SO248 (BacGeoPac), M139 (MerMet 17-97), MOBYDICK and POSEIDON. This study was supported by JSPS KAKENHI Grant (23651004) to M.U., the Austrian Science Fund (FWF) project I486-B09, Z194, P28781-B21 and P35587-B to G.J.H., P27696-B22 to E.S. and P23221-B11 to T.R., and the European Research Council under the European Community’s Seventh Framework Program (FP7/2007-2013)/ERC grant agreement (MEDEA project 268595) to G.J.H. C.A. was supported by JSPS Postdoctoral Fellowships for Research Abroad (H26–168), the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie no. 701324 and ERC Advanced Grant (TACKLE project, 695192)., Peer reviewed