Wetland tree barks are dynamic hotspots for microbial trace gas cycling

• DOI: 10.1101/2024.07.02.601631
• Publication Date: 2024-07-04T04:35:25Z
• Authors: Pok Man Leung; Luke C Jeffrey; Sean K Bay; Paula Gomez-Alvarez; Montgomery Hall; Scott G Johnston; Johannes Dittmann; Thanavit Jirapanj...; Tess F Hutchinson; Nicholas V Coleman; Xiyang Dong; Elizabeth Deschas...; Damien T Maher; Chris Greening
• Keywords: Biogeochemical Cycle; Cycling; Biogeochemistry; Trace gas

Wetland tree stems have recently been shown to be a major source of methane emissions. However, the microbial communities associated within these (the caulosphere) and their contribution biogeochemical cycling other compounds remain poorly understood. Here, we reveal that specialised inhabit bark multiple Australian species actively mediate methane, hydrogen, climate-active trace gases. Based on genome-resolved metagenomics, most bark-associated bacteria are hydrogen metabolisers facultative fermenters, adapted dynamic redox substrate conditions. Over three quarters assembled genomes encoded genes for metabolism, including novel lineages Acidobacteriota, Verrucomicrobiota, candidate phylum JAJYCY01. Methanotrophs such as Methylomonas were abundant in certain trees coexisted with hydrogenotrophic methanogenic Methanobacterium. Bark-associated microorganisms mediated aerobic oxidation carbon monoxide, at concentrations seen planta, but under anoxic conditions barks could become significant Field-based experiments upscaling analysis suggested quantitatively mediators global cycling, mitigating climatically-active gas emissions from contributing net terrestrial sink atmospheric hydrogen. These findings highlight caulosphere an important new research frontier understanding biogeochemistry.