© 2017 Ccorahua-Santo et al. An arsenic resistance genomic island in the bacterium Klebsiella michiganensis 3T412C was isolated from mine tailings from Peru. This genomic island confers adaptation to extreme environments with high concentrations of arsenic. Isolate 3T412C contained a complete set of genes involved in resistance to arsenic. This operon is surrounded by putative genes for resistance to other heavy metals.