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So far, numerous genes have been found to associate with various strategies to resist and transform the toxic metalloid arsenic(here, we denote these genes as "arsenic-related genes").However, our knowledge of the distribution, redundancies and organization of these genes in bacteria is still limited.In this study, we analyzed the 188 Burkholderialesgenomes and found that 95% genomes harbored arsenic-related genes, with an average of 6.6 genes per genome.The results indicated: a) compared to a low frequency of distribution for aio(arseniteoxidase) (12 strains), arr (arsenate respiratory reductase) (1 strain) and arsM (arsenitemethytransferase)-like genes (4 strains), thears (arsenic resistance system)-like genes were identified in 174 strainsincluding 1,051 genes;b) 2/3 ars-like genes were clustered as ars operon and displayed a high diversity of gene organizations(68 forms) which may suggest the rapid movement and evolution for ars-like genes in bacterial genomes;c) the arscnite effiux system was dominant withACR3 form rather thanArsB inBurkholderiales; d)only a few numbers of arsMand arrABare found indicatingneither As Ⅲ biomethylationnorAsV respirationisthe primary mechanisminBurkholderialesmembers; (e) the aio-like gene isrnostly flanked with ars-like genes andphosphate transport system, implying the close functional relatedness between arsenic and phosphorus metabolisms.On average, the number of arsenic-related genesper genome of strains isolated from arsenic-rich environments is more than four times higher than the strains from other environments.Compared with human, plant and animal pathogens, the environmental strainspossess a larger average number of arsenic-related genes, which indicates that habitat is likely a key driver for bacterialarsenic resistance.