Impact of hydrostatic pressure on organic carbon cycling of the deep-sea microbiome

• Published in: bioRxiv
• Main Authors: Amano, Chie, Zhao, Zihao, Sintes, Eva, Reinthaler, Thomas, Stefanschitz, Julia, Kisadur, Murat, Utsumi, Motoo, Herndl, Gerhard J
• Format: Paper
• Language: English
• Published: Cold Spring Harbor Cold Spring Harbor Laboratory Press 31.03.2022
• Subjects: Carbon cycle; Deep sea; Metabolism; Microbiomes; Prokaryotes
• DOI: 10.1101/2022.03.31.486587

Deep-sea microbial communities are exposed to high hydrostatic pressure. While some of these deep-sea prokaryotes are adapted to high-pressure conditions, the contribution of piezophilic (i.e., pressure-loving) and piezotolerant prokaryotes to the total deep-sea prokaryotic community remains unknown. Here we show that the metabolic activity of prokaryotic communities is increasingly inhibited with increasing hydrostatic pressure. At 4,000 m depth, the bulk heterotrophic prokaryotic activity under in situ hydrostatic pressure was only about one-third of that measured on the same community at atmospheric pressure conditions. Only ~5% of the bathypelagic prokaryotic community are piezophilic while ~85% of the deep-sea prokaryotes are piezotolerant. A small fraction (~10%) of the deep-sea prokaryotes is piezosensitive (mainly members of Bacteroidetes, Alteromonas) exhibiting specific survival strategies at meso- and bathypelagic depths. These piezosensitive bacteria elevated their activity by more than 100-fold upon depressurization. Hence, the consistently higher bulk metabolic activity of the deep-sea prokaryotic community measured upon depressurization is due to a rather small fraction of the prokaryotic community. Overall, the heterotrophic prokaryotic activity in the deep-sea is substantially lower than hitherto assumed with major impacts on the oceanic carbon cycling. Competing Interest Statement The authors have declared no competing interest.