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© 2021. This work is published under https://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.

Abstract

Marine sedimentation rate and bottom-water O2 concentration control organic carbon remineralization and sequestration across continental margins, but whether and how they shape microbiome architecture (the ultimate effector of all biogeochemical phenomena) across shelf and slope sediments is still unclear. Here we reveal distinct microbiome structures and functions, amidst comparable pore fluid chemistries, along 300 cm sediment horizons underlying the seasonal (shallow coastal; water depth: 31 m) and perennial (deep sea; water depths: 530 and 580 m) oxygen minimum zones (OMZs) of the Arabian Sea, situated across the western Indian margin. The sedimentary geomicrobiology was elucidated by analyzing metagenomes, metatranscriptomes, enrichment cultures, and depositional rates measured via radiocarbon and lead excess dating; the findings were then evaluated in light of the other geochemical data available for the cores. Along the perennial-OMZ sediment cores, microbial communities were dominated byGammaproteobacteria and Alphaproteobacteria, but in the seasonal-OMZ core communities were dominated by Euryarchaeota and Firmicutes. As a perennial-OMZ signature, a cryptic methane production–consumption cycle was found to operate near the sediment surface, within the sulfate reduction zone; overall diversity, as well as the relative abundances of anaerobes requiring simple fatty acids (methanogens, anaerobic methane oxidizers, sulfate reducers, and acetogens), peaked in the topmost sediment layer and then declined via synchronized fluctuations until the sulfate–methane transition zone was reached. The microbiome profile was completely reversed in the seasonal-OMZ sediment horizon. In the perennial-OMZ sediments, deposited organic carbon was higher in concentration and rich in marine components that degrade readily to simple fatty acids; simultaneously, lower sedimentation rate afforded higherO2 exposure time for organic matter degradation despite perennial hypoxia in the bottom water. The resultant abundance of reduced carbon substrates eventually sustained multiple inter-competing microbial processes in the upper sediment layers. The entire geomicrobial scenario was opposite in the sediments of the seasonal OMZ. These findings create a microbiological baseline for understanding carbon–sulfur cycling in distinct depositional settings and water column oxygenation regimes across the continental margins.

Details

Title
Sedimentation rate and organic matter dynamics shape microbiomes across a continental margin
Author
Bhattacharya, Sabyasachi 1 ; Mapder, Tarunendu 2 ; Fernandes, Svetlana 3 ; Roy, Chayan 1 ; Sarkar, Jagannath 1 ; Moidu, Jameela Rameez 1   VIAFID ORCID Logo  ; Mandal, Subhrangshu 1 ; Sar, Abhijit 4 ; Chakraborty, Amit Kumar 5 ; Mondal, Nibendu 1 ; Chatterjee, Sumit 1 ; Dam, Bomba 4 ; Peketi, Aditya 3 ; Chakraborty, Ranadhir 6 ; Mazumdar, Aninda 3 ; Ghosh, Wriddhiman 1   VIAFID ORCID Logo 

 Department of Microbiology, Bose Institute, P-1/12 CIT Scheme VIIM, Kolkata – 700054, West Bengal, India 
 Department of Chemistry, Bose Institute, 93/1 APC Road, Kolkata – 700009, India; present address: Division of Clinical Pharmacology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA 
 Gas Hydrate Research Group, Geological Oceanography, CSIR National Institute of Oceanography, Dona Paula, Goa – 403004, India 
 Department of Botany, Institute of Science, Visva-Bharati, Santiniketan, West Bengal – 731235, India 
 Department of Environmental studies, Institute of Science, Visva-Bharati, Santiniketan, West Bengal – 731235, India 
 Department of Biotechnology, University of North Bengal, Siliguri, West Bengal 734013, India 
Pages
5203-5222
Publication year
2021
Publication date
2021
Publisher
Copernicus GmbH
ISSN
17264170
e-ISSN
17264189
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2575224041
Copyright
© 2021. This work is published under https://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.