Fig. 3.

Ecological functions of Anaeromyxobacter and Geobacter, belonging to Deltaproteobacteria, predominant in paddy soils, expanded by metatranscriptomics in this study. Anaeromyxobacter and Geobacter, ubiquitously predominant in paddy soils, are key player groups in the reduction of iron and manganese, which actively progresses in paddy soils soon after waterlogging (3, 4, 7, 9, 11, 20, Fig. 1B, S2B). Metatranscriptomics in this study suggested that these genera also associate with reductive nitrogen transformation, i.e., denitrification, DNRA, and nitrogen fixation. Sketches of Anaeromyxobacter and Geobacter are based on electron microscope photographs published elsewhere (3, 16). †, NO₂⁻ reduction to NO is driven by common denitrifiers within Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria (5), not by Anaeromyxobacter and Geobacter within Deltaproteobacteria; ‡, Anaeromyxobacter reduce N₂O to N₂, whereas Geobacter do not (Table S1).