## Results and Discussion
### Genes Potentially Conferring Metal Resistance in Strain SRS-W-1-2016  
One notable attribute of the _Arthrobacter_ genus is their ability to degrade xenobiotic compounds and resistance to heavy metals [26; 31; 32; 33; 34], including U and Ni [27]. Genome-centric assessment of strain SRS-W-1-2016 revealed the presence of several gene homologues previously demonstrated to play a part in the resistance against heavy metal/radionuclides, such as several efflux and MFS transporters, P-type ATPase translocators, and heavy metal-responsive transcriptional regulators. Specifically, for metals resistance, the genome of strain SRS-W-1-2016 contains the high affinity transport system for nickel/cobalt (_NiCoT_ gene; _HoxN/HupN/NixA_ family), as well as the cobalt/zinc/cadmium resistant protein (_CzcD_). The _NiCoT_ system, shown relative to four homologous gene systems (Figure 4a), was found to occur as a 1056 bp fragment (contig41300; fig! 666666.232708.peg.2084), while the _CzcD_ subsystem, (Figure 4b) was a 1089 bp gene fragment (contig51456; fig! 666666.232708.peg.2658), respectively. In addition to these genes, bacterial resistance to metals is also governed by genes for the resistance, nodulation, and cell division (RND) family proteins- all part of transenvelope protein complexes which detoxify the cellular environment by exporting toxic metal cations from the periplasm to the outside. Several RND-type efflux gene homologues were found interspersed within the genome of strain SRS-W-1-2016 (data not shown). Additionally, the ABC-type transporters and heavy-metal transport/detoxification proteins were abundantly present within the genome of strain SRS-W-1-2016, potentially maintaining metal homeostasis and survival in the SRS co-contaminated soil habitat. There are several mechanisms by which bacteria can reduce the mobility and hence toxicity of U and one process that shows bioremediation potential is by a phosphatase enzyme mediated biotransformation of U (VI) into phosphate-minerals [27; 29]. It has been demonstrated that microbially-mediated alkaline or acid phosphatase activities can result in the precipitation of more than 90% of soluble U, resulting in the formation of a wide array of uranyl phosphate minerals [30]. Therefore, the microbially-mediated formation of uranyl phosphate from U (VI) warrants further research for the control of U mobility in U.S. DOE contaminated environments. To identify the presence  
Figure 4: Shown are (**a**) the chromosomal region of the cobalt/zinc/cadmium subsystem gene (1056 bp) in _Arthrobacter_ sp. strain SRS-W-2-2016 relative to four other organisms and (**b**) the _HoxN/HupN/NixA_ family nickel/cobalt transporter gene (1089 bp) in _Arthrobacter_ sp. strain SRS-W-2-2016 relative to four other organisms. The graphic is centered on the focus gene, which is red and numbered 1. Sets of genes with a similar sequence are grouped with the same number and color. Genes whose relative position is conserved in at least four other species are functionally coupled and share gray background boxes. of the phosphatase enzyme within the genome of strain SRS-W-1-2016, we manually queried the annotated genome, revealing the presence of two acid phosphatases (NCBI gene accession # OOP63314 and OOP61946), as well as an alkaline phosphatase (NCBI gene accession # OOP64358). Moreover, we also identified the _spoT_ gene (contig50361; fig1666666.232708.peg.2556) in strain SRS-W-1-2016 (data not shown); the _spoT_ gene encodes a guanosine tetraphosphate (ppGpp) hydrolase/syntetase which was recently implicated in the resistance of U by _Caulobacter crescentus_, but only under carbon starvation conditions [35]. Collectively, these mechanisms likely render the metabolic ability to strain SRS-W-1-2016 to not only survive in the SRS soils, but also perform critical biodegradable functions.