Unveiling Microbial Adaptations to High CO2 Environments: Metagenomic Insights from the Eger Rift (Czech Republic)

Introduction
High CO₂ environments, such as the Hartoušov mofette system in Central Europe"s Eger Rift, harbor diverse microbial communities critical for understanding carbon cycling and extreme condition adaptation¹. Metagenomic analysis has emerged as a powerful tool for combing the genetic makeup and metabolic capabilities of these microbial communities.
Goals
In this study, our objective was to characterize the microbial composition in the CO₂-rich environment at the Eger Rift site. Additionally, we analyzed their metabolic potential, focusing on carboxylation reactions involved in fixing CO₂ in cellular material.
Methods
Drill core and water samples were collected from various depths within a drill hole at the Eger Rift site and subjected to metagenomic sequencing. Taxonomic profiles were determined using Kaiju and Kraken2. Metagenome-Assembled Genomes (MAGs) were generated for single organisms, and gene prediction (Prodigal) and functional annotation (eggNOG-mapper) were performed.
Results
Metagenomic data analysis unveiled a diverse taxonomic landscape of bacteria and archaea in the high CO₂ environment of the Eger Rift. Predominant phyla in drill core samples included Pseudomonadota and Cyanobacteria, while Firmicutes, Pseudomonadota, and Bacteroidetes dominated water samples.
Two high-quality MAGs were retrieved from the metagenomic samples. One MAG could be identified as the genome of an archaeon, Methanobacterium paludis, which shows an estimated average nucleotide identity of 89.84% and 93.62% with the published reference organisms. The other MAG was affiliated with the genus Proteiniphilum. Within these MAGs, the presence of diverse carbon fixation pathways, including key enzymatic steps and metabolic routes, was identified.
Summary
Our study extensively explored taxonomic diversity, functional potential, and genetic adaptations in the CO₂-rich Hartoušov mofette system. These insights into carbon fixation pathways hold promise for CO₂-based biotechnological advancements.
References
1. Liu, Q. et al. Microbial Signatures in Deep CO₂-Saturated Miocene Sediments of the Active Hartoušov Mofette System (NW Czech Republic). Front. Microbiol. 11, (2020)