The versatile soil bacterium lacks the hallmark denitrification genes and (NO→NO), and couples growth to NO reduction to NH (respiratory ammonification) and to NO reduction to N also grows by reducing Fe(III) to Fe(II), which chemically reacts with NO to form NO (i.e., chemodenitrification). Following the addition of 100 μmoles of NO or NO to Fe(III)-grown, axenic cultures of , 54 (±7) μmoles and 113 (±2) μmoles NO-N, respectively, were produced and subsequently consumed. The conversion of NO to N in the presence of Fe(II) through linked biotic-abiotic reactions represents an unrecognized ecophysiology of The new findings demonstrate that the assessment of gene content alone is insufficient to predict microbial denitrification potential and N loss (i.e., the formation of gaseous N products). A survey of complete bacterial genomes in the NCBI Reference Sequence database coupled with available physiological information revealed that organisms lacking but with Fe(III) reduction potential and genes for NO and NO reduction are not rare, indicating that NO reduction to N through linked biotic-abiotic reactions is not limited to Considering the ubiquity of iron in soils and sediments and the broad distribution of dissimilatory Fe(III) and NO reducers, denitrification independent of NO-forming NO reductases (through combined biotic-abiotic reactions) may have substantial contributions to N loss and NO flux. Current attempts to gauge N loss from soils rely on the quantitative measurement of and genes and/or transcripts. In the presence of iron, the common soil bacterium is capable of denitrification and producing N without the key denitrification genes Such chemodenitrifiers denitrify through combined biotic and abiotic reactions and have potentially large contributions to N loss to the atmosphere, and fill a heretofore unrecognized ecological niche in soil ecosystems. The findings emphasize that comprehensive understanding of N flux and accurate assessment of denitrification potential can only be achieved when integrated studies of interlinked biogeochemical cycles are performed.