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Novel Methanosarcinaceae species Methanohalophilus methylutens sp. nov., Methanolobus methylotrophicus sp. nov., and Methanococcoides guerreronegronense sp. nov. from Guerrero Negro hypersaline microbial mats in accordance with the SeqCode
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DOI:10.1016/j.syapm.2026.126716.png)
Abstract
En 中文
The Methanosarcinaceae family is the most versatile among methanogenic archaea, utilizing a wide variety of substrates for methanogenesis. It includes all known halophilic, methylotrophic methanogens. Despite evidence of their presence and even dominance over other methanogenic taxa in Guerrero Negro hypersaline microbial mats, no archaeal species have been cultured or described to date. Consequently, a significant gap remains in our understanding of their metabolic potential and diversity. In this study, seven high-quality metagenome-assembled genomes (MAGs) affiliated with the Methanosarcinaceae family were reconstructed. Three MAGs (E22BA4_117TS, E22_A5_bin58TS, and E22bin_1538TS) serve as the nomenclatural type for the novel proposed species Methanohalophilus methylutens, Methanolobus methylotrophicus, and Methanococcoides guerreronegronense, according to the SeqCode rules and representing the first Methanosarcinaceae species described from microbial mats of Guerrero Negro. Based on genomic content and phylogenetic features, we infer that these MAGs are cytochrome-containing methanogens supported by the presence of core methanogenesis genes (fwd/fmd, ftr, mch, mtd, mer, mtr and mcr). They exhibit distinct metabolic strategies: E22BA4_117TS is a generalist with broad substrate versatility, E22_A5_bin58TS is an expanded methylotrophic specialist, and E22bin_1538TS is a narrow-range methylotroph. All three MAGs encode the complete set of genes for the methylotrophic pathway, multiple Na+/H+ antiporters and both transport and biosynthesis genes for compatible solutes, collectively indicative of their adaptations to hypersaline conditions. These novel species enrich the phylogenomic resolution of Methanosarcinaceae and expand current understanding of the diversity and ecological relevance of these methanogenic archaea in hypersaline ecosystems, while providing genomic evidence that clarifies their metabolic potential and adaptations.
Keywords:
Methanosarcinaceae
methanogenic archaea
hypersaline microbial mats
metagenome-assembled genomes
methylotrophic methanogens
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