Ethanoperedens thermophilium
Classification
Archaea; Euryarchaeota; Stenosarchaea; Methanomicrobia; Methanosarcinales; Methanosarcinales incertae sedis; GOM Arc I cluster
Species
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NCBI: [1] |
Candidatus Ethanoperedens thermophilum
Description and Significance
Candidatus Ethanoperedens thermophilum is a thermophilic archaeon known to mediate the anaerobic oxidation of ethane in cold seeps and hydrothermal vents. Although this type of extremophile has been previously challenging to study due to its inherently slow growth, this specific archaeon has recently been cultured using hydrothermal sediments of the Guaymas Basin (Gulf of California), with ethane as the substrate, in order to understand the mechanisms of archaeal alkane degradation (Hahn et al., 2020). With a fully sequenced genome, this primarily cocci archaeon could be a solution to a variety of knowledge gaps surrounding microorganisms and seafloor habitats.
Genome Structure
Similar to other microorganisms, the genome of Candidatus Ethanoperedens thermophilum is a single, circular chromosome. In order to understand the genomic makeup of the GoM-Arc1 genome, cultures were performed in both 37 degrees Celsius and 50 degrees Celsius resulting in a 76.2% genome completeness and 100% complete genetic sequence, respectively. Due to their 98% similarity, both samples were able to be fully sequenced after long-read DNA sequencing (Hahn et al., 2020).
The total length of the genome was found to be 1.25Mb with a protein count of 1,274 and a gene count of 1,329. There is also a GC content of 41.3%. When comparing metagenome-assembled genomes (MAGs) and 16S rRNA of this novel organism to others of the GoM-Arc1 clade derived from the Guaymas Basin and the Gulf of Mexico, it is apparent that they have similar gene contents (over 90% average nucleotide identity (ANI) and 99.5% 16S rRNA gene identity) - ultimately suggesting that these GoM-Arc1 archaea are ethane oxidizers (Hahn et al., 2020).
Cell Structure, Metabolism and Life Cycle
Candidatus Ethanoperedens thermophilum is produced from hydrothermally heated, hydrocarbon-rich marine sediment from 2000m below sea level in the Guaymas Basin of the Gulf of California, Mexico. This archaeon is mostly coccoid, about 0.7 μm in diameter, and forms large, irregular clusters in large dual-species consortia with its sulfate-reducing partner bacterium: “Candidatus Desulfofervidus auxilii” (Hahn et al., 2020).
Candidatus Ethanoperedens thermophilum is an ethane-oxidizing, heat-loving archeon that couples its mechanisms with sulfate-reducing bacteria on the seafloor in order to completely degrade ethane. A growth experiment showed that ethane was completely oxidized while sulfate was reduced to sulfide according to the formula 4C2H6 + 7SO42− → 8HCO3− + 7HS− + 4H2O + H+ when this archeon was cultured with its partner bacterium in vitro (Hahn et al., 2020).
Archeon of this nature are typically very slow replicators and thus, very challenging to study in lab cultures. However, this strain of ethane metabolizer doubles its population in cell culture every week. This quick replication time has allowed researchers to put together a complete gene sequence of its GoM-Arc1 genome, which contains similar genes encoding the enzymes of the methanogenesis pathway, including a highly similar divergent-type MCR, and the Wood-Ljungdahl pathway. However, there is no pathway for beta-oxidation of longer-chain fatty acids which has further prompted researchers to believe that it is likely that it is an ethane oxidizer (Hahn et al., 2020).
Ecology and Pathogenesis
Researchers discovered Candidatus Ethanoperedens thermophilum, a previously unknown microbe, in the seafloor of the Guaymas Basin at a depth of 2000 meters in the Gulf of California. This organism thrives in the hot vent environment provided by hydrothermal vents where it is of no concern as a possible pathogen, and in consortium with a sulfate-reducing bacteria, it has the ability to totally degrade ethane.
The discovery of this archaeon is significant for two primary reasons: it is the first ethane-degrading archaea with the ability to be cultured in the lab within a week and it is able to reverse its consumption of ethane to CO2 in order to produce ethane from CO2. Although the exact mechanism of this is not well understood, it is possible that - with continued research - it will be implemented as a way to extract CO2 from the atmosphere.
References
Cedric Jasper Hahn , Rafael Laso-Pérez , Francesca Vulcano , Konstantinos-Marios Vaziourakis , Runar Stokke , Ida Helene Steen , Andreas Teske , Antje Boetius , Manuel Liebeke , Rudolf Amann , Katrin Knittel , and Gunter Wegener. “Candidatus Ethanoperedens,” a Thermophilic Genus of Archaea Mediating the Anaerobic Oxidation of Ethane. 2020 Apr 21. ASM Journals, mBio; Vol. 11, No. 2.
Hahn CJ, Laso-Pérez R, Vulcano F, Vaziourakis KM, Stokke R, Steen IH, Teske A, Boetius A, Liebeke M, Amann R, Knittel K, Wegener G. "Candidatus Ethanoperedens," a Thermophilic Genus of Archaea Mediating the Anaerobic Oxidation of Ethane. mBio. 2020 Apr 21;11(2):e00600-20. doi: 10.1128/mBio.00600-20. PMID: 32317322; PMCID: PMC7175092.
Author
Page authored by Brady Antolick, a student of Prof. Bradley Tolar at UNC Wilmington.
