Summary Bradyrhizobia are common members of soil microbiomes and known as N 2 ‐fixing symbionts of economically important legumes. Many are also denitrifiers, which can act as sinks or sources for N 2 O. Inoculation with compatible rhizobia is often needed for optimal N 2 ‐fixation, but the choice of inoculant may have consequences for N 2 O emission. Here, we determined the phylogeny and denitrification capacity of Bradyrhizo...

Summary Fungal denitrification is claimed to produce non‐negligible amounts of N 2 O in soils, but few tested species have shown significant activity. We hypothesized that denitrifying fungi would be found among those with assimilatory nitrate reductase, and tested 20 such batch cultures for their respiratory metabolism, including two positive controls, Fusarium oxysporum and Fusarium lichenicola , throughout the transition fr...

Summary Bradyrhizobia are abundant soil bacteria, which can form nitrogen‐fixing symbioses with leguminous plants, including important crops such as soybean, cowpea and peanut. Many bradyrhizobia can denitrify, but studies have hitherto focused on a few model organisms. We screened 39 diverse Bradyrhizobium strains, isolated from legume nodules. Half of them were unable to reduce N 2 O, making them sources of this greenhouse g...

Epiphytes are hyper‐diverse and one of the frequently undervalued life forms in plant surveys and biodiversity inventories. Epiphytes of the Atlantic Forest, one of the most endangered ecosystems in the world, have high endemism and radiated recently in the Pliocene. We aimed to (1) compile an extensive Atlantic Forest data set on vascular, non‐vascular plants (including hemiepiphytes), and lichen epiphyte species occurrence a...

Summary B acillus vireti is a nitrate‐ammonifying bacterium and a partial denitrifier, reducing NO 3 − , NO 2 − , NO and N 2 O with NarG , NrfA , CbaA and NosZ respectively. Growth is optimized through successive use of the electron acceptors O 2 and NO 3 − , followed by NO 2 − , NO and N 2 O . Fermentation takes place simultaneously with anaerobic respiration. When grown in batch culture with 5 mM initial NO 3 − , transcripti...

Summary Several G ram‐positive bacteria carry genes for anaerobic reduction of NO 3 − via NO 2 − to NH 4 + or gaseous nitrogen compounds, but the processes are understudied for these organisms. Here, we present results from a whole‐genome analysis of the soil bacterium B acillus vireti and a phenotypic characterization of intermediate and end‐products, formed under anoxic conditions in the presence of NO 3 − . B acillus vireti...