Biogeochemical and omic evidence for multiple paradoxical methane production mechanisms in freshwater lakes

摘要: Abstract Aquatic ecosystems are globally significant sources of the greenhouse gas methane (CH4) to atmosphere. However, CH4 is produced ‘paradoxically’ in oxygenated water via at least three mechanisms, fundamentally limiting our understanding overall production. Here we resolve these production mechanisms through measurements, δ13CH4 analyses, 16S rRNA sequencing, and metagenomics/transcriptomics applied freshwater incubation experiments with multiple time points treatments (addition a methanogenesis inhibitor, dark, high-light). We captured paradoxical production, but show that was an unlikely source. In contrast, abundant bacteria metabolized methylphosphonate—similar observations marine ecosystems. Metatranscriptomics stable isotopic analyses experimental also identified potential mechanism linked (bacterio)chlorophyll metabolism by Cyanobacteria especially Proteobacteria. Variability across indicates multiple, widely-distributed bacterial groups pathways can produce substantial quantities aquatic