High-quality PacBio draft genome sequences of 17 free-living Bradyrhizobium and four related Nitrobacteraceae strains isolated from arid soils in the Santa Catalina Mountains of Southern Arizona

Non-symbiotic <i>Bradyrhizobium</i> are among the most abundant and ubiquitous microbes in bulk soils globally. Despite this, most available genomic resources for <i>Bradyrhizobium</i> are derived from plant-associated strains. We present high-quality draft genomes for 17 <i>Bradyrhizobium</i> and four <i>Nitrobacteraceae</i> cultures isolated from bulk semiarid soils in Arizona, USA. The genome sizes range from 5.99 to 10.4 Mbp. Phylogenomic analysis of the 21 genomes indicates they fall into four clades. Two of the clades are nested within the <i>Bradyrhizobium</i> genus. The other two clades were associated with <i>Nitrobacteraceae</i> outgroups basal to <i>Bradyrhizobium</i>. All genomes lack genes coding for molybdenum or vanadium nitrogenases, and <i>nod</i> genes that code for proteins involved in nodulation, suggesting these isolates are free-living, non-symbiotic and do not fix dinitrogen gas. These genomes offer new resources for investigating free-living <i>Bradyrhizobium</i> lineages.