ARPHA Conference Abstracts :
Conference Abstract
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Corresponding author: Maliheh Mehrshad (maliheh.mehrshad@slu.se)
Received: 14 Jun 2023 | Published: 13 Oct 2023
© 2023 Maryam Rezaei Somee, Carolina González-Rosales, Stephanie Turner, Stefan Bertilsson, Mark Dopson, Maliheh Mehrshad
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Rezaei Somee M, González-Rosales C, Turner S, Bertilsson S, Dopson M, Mehrshad M (2023) Survival Strategies of High GC-Content Microorganisms in Oligotrophic Deep Groundwater. ARPHA Conference Abstracts 6: e107970. https://doi.org/10.3897/aca.6.e107970
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Deep groundwaters are among the most energy and nutrient-limited ecosystems on the planet. The limited resources are mainly due to the absence of photosynthesis-driven primary production (
A total of 1990 MAGs/SAGs with a completeness of ≥50% and <5% contamination were recovered from 43 metagenomic datasets. The taxonomy of the MAGs/SAGs was assigned using the GTDB-tk (
The GC content and estimated genome size (EGS) of the recovered MAGs/SAGs were linearly correlated, suggesting that higher genome-level GC content is associated with larger genome size. The most common taxa among high GC (≥50%) content MAGs/SAGs were affiliated with the phyla Proteobacteria, Desulfobacterota, Actinobacteriota, Chloroflexota, and Patescibacteria. Analysis of metabolic modules in the environmental context revealed that high GC content MAGs constituted the main primary producers in all investigated groundwaters. Among the seven investigated C-fixation pathways, routes leading to the production of intermediates of reductive tricarboxylic acid (rTCA) were significantly enriched in high GC-content genomes. Both carboxylation/reduction first CO2-capturing enzymes were significantly enriched in MAGs with high GC contents. Of the various carbon fixation strategies, rGly and rTCA are the most energy-efficient and consume one and three ATP molecules, respectively (
High GC content MAGs/SAGs appear to be metabolically versatile and capable of acquiring nutrients via different carbon and nitrogen fixation pathways along with various C-scavenging strategies for substrate uptake to acquire energy and survive in oligotrophic conditions. Although their larger genome size and higher GC content entail higher expenses for replication and maintenance, their presence within the community of deep groundwater is supported by the “Black Queen Theory”. According to this theory, a cell containing an expensive metabolic pathway is maintained within the community as it provides a service that other members cannot.
deep groundwater, GC-rich genomes, carbon fixation, nitrogen fixation
Maryam Rezaei Somee
ISEB-ISSM 2023
Linnaeus University