In:
The ISME Journal, Springer Science and Business Media LLC, Vol. 17, No. 1 ( 2023-01), p. 95-104
Abstract:
Serpentinization of ultramafic rocks provides molecular hydrogen (H 2 ) that can support lithotrophic metabolism of microorganisms, but also poses extremely challenging conditions, including hyperalkalinity and limited electron acceptor availability. Investigation of two serpentinization-active systems reveals that conventional H 2 -/CO 2 -dependent homoacetogenesis is thermodynamically unfavorable in situ due to picomolar CO 2 levels. Through metagenomics and thermodynamics, we discover unique taxa capable of metabolism adapted to the habitat. This included a novel deep-branching phylum, “ Ca . Lithacetigenota”, that exclusively inhabits serpentinite-hosted systems and harbors genes encoding alternative modes of H 2 -utilizing lithotrophy. Rather than CO 2 , these putative metabolisms utilize reduced carbon compounds detected in situ presumably serpentinization-derived: formate and glycine. The former employs a partial homoacetogenesis pathway and the latter a distinct pathway mediated by a rare selenoprotein—the glycine reductase. A survey of microbiomes shows that glycine reductases are diverse and nearly ubiquitous in serpentinite-hosted environments. “ Ca . Lithacetigenota” glycine reductases represent a basal lineage, suggesting that catabolic glycine reduction is an ancient bacterial innovation by Terrabacteria for gaining energy from geogenic H 2 even under hyperalkaline, CO 2 -poor conditions. Unique non-CO 2 -reducing metabolisms presented here shed light on potential strategies that extremophiles may employ for overcoming a crucial obstacle in serpentinization-associated environments, features potentially relevant to primordial lithotrophy in early Earth.
Type of Medium:
Online Resource
ISSN:
1751-7362
,
1751-7370
DOI:
10.1038/s41396-022-01197-9
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2023
detail.hit.zdb_id:
2299378-2
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