Microbial Diversity and Function in Shallow Subsurface Sediment and Oceanic Lithosphere of the Atlantis Massif.

J Goordial,T D’Angelo,J M Brown,N J Poulton,G L Früh-Green,J M Labonté,B N Orcutt,R Stepanauskas,Nicole Dubilier

doi:10.1128/mbio.00490-21

J Goordial, T D’Angelo + Show 7 more

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https://doi.org/10.1128/mbio.00490-21

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Journal: mBio	Publication Date: Aug 3, 2021
Citations: 13	License type: CC BY 4.0

Affiliation: Bigelow Laboratory for Ocean Sciences, University of Guelph

Abstract

ABSTRACTThe marine lithospheric subsurface is one of the largest biospheres on Earth; however, little is known about the identity and ecological function of microorganisms found in low abundance in this habitat, though these organisms impact global-scale biogeochemical cycling. Here, we describe the diversity and metabolic potential of sediment and endolithic (within rock) microbial communities found in ultrasmall amounts (101 to 104 cells cm−3) in the subsurface of the Atlantis Massif, an oceanic core complex on the Mid-Atlantic Ridge that was sampled on International Ocean Discovery Program (IODP) Expedition 357. This study used fluorescence-activated cell sorting (FACS) to enable the first amplicon, metagenomic, and single-cell genomic study of the shallow (<20 m below seafloor) subsurface of an actively serpentinizing marine system. The shallow subsurface biosphere of the Atlantis Massif was found to be distinct from communities observed in the nearby Lost City alkaline hydrothermal fluids and chimneys, yet similar to other low-temperature, aerobic subsurface settings. Genes associated with autotrophy were rare, although heterotrophy and aerobic carbon monoxide and formate cycling metabolisms were identified. Overall, this study reveals that the shallow subsurface of an oceanic core complex hosts a biosphere that is not fueled by active serpentinization reactions and by-products.

Highlights

The marine lithospheric subsurface is one of the largest biospheres on Earth; little is known about the identity and ecological function of microorganisms found in low abundance in this habitat, though these organisms impact global-scale biogeochemical cycling
We describe the diversity and metabolic potential of sediment and endolithic microbial communities found in ultrasmall amounts (101 to 104 cells cm23) in the subsurface of the Atlantis Massif, an oceanic core complex on the Mid-Atlantic Ridge that was sampled on International Ocean Discovery Program (IODP) Expedition 357
This study reveals that the shallow subsurface of an oceanic core complex hosts a biosphere that is not fueled by active serpentinization reactions and by-products

Summary

Introduction

The marine lithospheric subsurface is one of the largest biospheres on Earth; little is known about the identity and ecological function of microorganisms found in low abundance in this habitat, though these organisms impact global-scale biogeochemical cycling. We describe the diversity and metabolic potential of sediment and endolithic (within rock) microbial communities found in ultrasmall amounts (101 to 104 cells cm23) in the subsurface of the Atlantis Massif, an oceanic core complex on the Mid-Atlantic Ridge that was sampled on International Ocean Discovery Program (IODP) Expedition 357. IMPORTANCE The subsurface rock beneath the ocean is one of the largest biospheres on Earth, and microorganisms within influence global-scale nutrient cycles This biosphere is difficult to study, in part due to the low concentrations of microorganisms that inhabit the vast volume of the marine lithosphere. The central dome of the Atlantis Massif was previously drilled during Integrated Ocean Drilling Program Expeditions 304/305, but this gabbroic-rich section was likely not representative of the crustal conditions underlying Lost City [14]

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