xoxF-linked methanol oxidation signals recur across wetland metagenomes

Wetlands are globally important methane-cycling ecosystems, but methanol oxidation remains less frequently emphasized than methane oxidation in community-level metagenomic analyses. Recent studies have highlighted the ecological importance of the lanthanide-dependent methanol dehydrogenase XoxF, yet wetland-focused xoxF literature remains comparatively limited relative to marine, freshwater, and other environmental systems. Here, we screened wetland-associated records in IMG/M using methane-metabolism and enzyme-centered queries focused on EC 1.1.2.10/xoxF and related methanol-oxidation annotations. Wetland-associated data sets repeatedly returned xoxF-linked annotations. We then examined a representative data set, a Wetland Surface Sediment combined assembly, to assess the relative representation of methanol-oxidation-associated annotations. In this co-assembly, xoxF/EC 1.1.2.10 was the most frequently recovered methanol-oxidation-associated annotation in the queried annotation space, with 1,996 genes, compared with 428 genes assigned to mxa-like EC 1.1.2.7 functions and 235 genes assigned to mdo/EC 1.1.99.37. KEGG-linked organism context included canonical methanotrophic and methylotrophic genera, including Methylococcus, Methylomonas, Methylotuvimicrobium, Methylovulum, and Methylophaga, while also extending into broader environmental Proteobacteria. Together, these data indicate that xoxF-linked methanol oxidation annotations recur across wetland metagenomes and are strongly represented in a representative wetland surface sediment co-assembly. Because this study relies on database annotations rather than organism-resolved pathway reconstruction or activity measurements, the results are best interpreted as community-level functional potential rather than evidence of xoxF-mediated activity, flux, or ecological dominance. These findings support wetlands as an underexamined but relevant setting for future clade-resolved, genome-resolved, and activity-resolved studies of xoxF-associated methanol oxidation.

Wetlands play a major role in Earth's methane cycle, but studies of wetland microbes often focus more on methane itself than on the downstream step of methanol oxidation. Our study shows that wetland metagenomes repeatedly contain strong signals for xoxF, a gene linked to lanthanide-dependent methanol oxidation. In a representative wetland surface sediment co-assembly, xoxF-associated annotations were much more abundant than classical methanol dehydrogenase annotations, suggesting that this pathway may be especially important in wetland microbial communities. Because most previous xoxF studies have focused on marine, freshwater, or other non-wetland systems, these findings highlight wetlands as an underexplored setting for methanol-processing metabolism. This work provides a foundation for future studies connecting these signals to specific microbes, environmental conditions, and methane-cycling processes in wetlands.