New bioavailable nitrogen (N) from biological nitrogen fixation (BNF) is critical for the N budget and productivity of marine ecosystems. Nitrogen-fixing organisms typically inactivate BNF when less metabolically costly N sources, like ammonium (NH 4 +), are available. Yet, several studies have observed BNF in benthic…

Sulfate reducing bacteria (SRB) comprise one of the few prokaryotic groups in which biological…

Biological fixation of dinitrogen (N2), the primary natural source of new bioavailable nitrogen (N) on Earth, is catalyzed by the enzyme nitrogenase through a complex mechanism at its active site metal cofactor. How this reaction functions in cellular environments, including its rate-limiting step, and how enzyme structure affects functioning…

Biological nitrogen fixation (BNF) by canonical molybdenum and complementary vanadium, and iron-only nitrogenase isoforms is the primary natural source of newly fixed nitrogen. Understanding controls on global nitrogen cycling requires knowledge of the isoform responsible for environmental BNF. The isotopic acetylene reduction assay (ISARA),…

Introduction After publication of this work, it was brought to our attention that it has not been tested whether R. palustris CGA009 and its derivative strains can use dimethyl sulfoxide (DMSO) as an electron sink (Luxem et al., 2020). Here, we report the results of additional bioinformatic, physiological, and chemical experiments to test…

Hydrogen (H2) gas is an obligatory byproduct of nitrogen (N2) reduction during biological nitrogen fixation by the metalloenzyme nitrogenase. Despite significant efforts, diazo- trophic H2 production rates remain too low to compete with fossil fuel-derived H2. Here, we investigate the role of temperature (14, 19, 30 C), carbon metabolism …

Understanding microbial niche differentiation along ecological and geochemical gradients is critical for assessing the mechanisms of ecosystem response to hydrologic variation and other aspects of global change. The lineage-specific biogeochemical roles of the widespread phylum Acidobacteria in hydrologically sensitive ecosystems, such as…