Microbiology & Virology

Physiological Trade-offs Drive The archaeal Dominance And Carbon Turnover In Deep Subsurface

By Keith Cowing

Status Report

Biorxiv.org

May 25, 2026

Filed under Archaea, Bacteria, Bathyarchaeia, biochemistry, biorxiv.org, deep biosphere, extremophile, genomics, Habitable Zone, Metabolism, multi-omics

Physiological Trade-offs Drive The archaeal Dominance And Carbon Turnover In Deep Subsurface — Conceptual framework of vertically stratified carbon cycling and microbial succession driven by physiological trade-offs in shelf sediments. Organic carbon (OC) reactivity and microbial community structure undergo profound transitions with sediment depth. In surface sediments, Bacteria (blue) drive a transient mineralization hotspot by rapidly consuming labile OC, whereas Archaea (pink) dictate the long-term fate and reactivity of the buried recalcitrant OC pool over geological timescales. These transition of OC degradation and microbial succession are underpinned by fundamental physiological trade-offs: whereas Bacteria prioritize rapid growth (G) with high energy investment near the surface, Archaea, primarily Bathyarchaeia, allocate more energy toward maintenance (M) and adaptation (A) by minimizing their growth rates in the deep subsurface. — biorxiv.org

Marine sediments host a vast deep biosphere, yet how microorganisms persist under severe energy limitation and govern long-term organic carbon (OC) preservation remains poorly understood.

Here we show that archaea, primarily Bathyarchaeia, systematically displace bacteria with depth and form net growth zones across East China Sea shelf deep sediments. Multi-omics analyses and bioenergetic modelling reveal that this transition is driven by sustained archaeal metabolism of diverse recalcitrant OC compounds, and a physiological trade-off that prioritizes cellular maintenance over growth, minimizing mortality in deep sediments.

This strategy triggers a fundamental shift in sedimentary carbon turnover: from rapid bacterial degradation of labile OC near the surface to persistent archaea-driven turnover of recalcitrant OC at depth. We estimate that Bathyarchaeia mediate ~77% of total OC degradation after 1,000 years of burial, corresponding to ~18% (~11.4 Pg C) of millennial OC degradation in global shelf sediments.

These findings identify subsurface archaea as key microbial regulators of long-term OC preservation and reveal how physiological trade-offs sustain life and carbon turnover in the energy-limited deep biosphere.

Physiological trade-offs drive the archaeal dominance and carbon turnover in deep subsurface, biorxiv.org

Astrobiology,

Keith Cowing

Biologist, Explorers Club Fellow, ex-NASA Space Biologist and Payload integrator, Editor of NASAWatch.com and Astrobiology.com, Lapsed climber, Explorer, Synaesthete, Former Challenger Center board member 🖖🏻

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