Genome-resolved metagenomics reveals non-methanogenic soil lineages in an Andean paramo wetland

Abstract

Wetlands are the largest natural source of atmospheric methane, and tropical wetlands are projected to drive the greatest increase in emissions under climate change, yet high-altitude tropical systems remain largely absent from global frameworks predicting this response. Here, we investigated soil metagenomes from the paramo ecosystem in Chingaza National Natural Park, Colombia, across three ecosites. Microbial community composition differed significantly among ecosites, with peatland soils exhibiting the highest diversity. Genome-resolved metagenomics recovered 109 high-quality metagenome-assembled genomes (MAGs); 8.3% (9 MAGs) could not be assigned to any described genus, representing phylogenetically novel lineages, while 37.6% (41 MAGs) were absent from the wetland-specific MUCC database but present in GTDB. Functional analyses revealed widespread Wood-Ljungdahl pathway potential, complemented by the bacterial reductive glycine pathway and reverse tricarboxylic acid cycle. No methanogenesis marker (mcrABG) was detected in any high- or medium-quality genomes or assembled contigs, identifying the genomically resolved community as non-methanogenic. A read-level search nonetheless recovered a low-abundance methanogen signal concentrated in peatland and affiliated with hydrogenotrophic lineages typical of acidic peatlands, indicating that methanogenesis is present but minor. Metabolic potential instead supported acetogenic carbon fixation and sulfate reduction, suggesting a carbon-cycling regime distinct from canonical methane-dominated wetlands. Together, these findings establish tropical alpine paramos as overlooked reservoirs of phylogenetically novel microbial diversity with metabolic potential distinct from other wetlands. Public release of these MAGs expands genomic representation of tropical alpine ecosystems and provides a foundation for improving predictions of carbon cycling in high-altitude ecosystems.