The demand for versatile bacterial strains which can be used in bioremediation of polycyclic aromatic hydrocarbons (PAHs) and arsenic co-contamination continues to grow as co-occurrence of two categories of hazardous material is continuously found.In this study, a microbial isolate, Pseudomonas sp.PAHAs-1, which can simultaneously reduce As(V) to As(Ⅲ) and degrade PAHs was isolated and characterized.This isolate completely reduced 1.5 mM As(V) within 48 h and removed approximately 100% and 50% of mixed PAHs (60 mg L-1 phenanthrene and 20 mg L-1 pyrene) within 60 h, respectively.It could reduce As(V) when this PAHs mixture was supplied as the sole carbon source under aerobic condition, but a slow arsenate reduction rate (4.62 μM h-1) was observed.The presence of arsenic also affected the cell growth and concurrent PAHs removal from solution, and this depended on PAH species and arsenic concentration.Adding sodium lactate to the medium provided a good option to enhance the arsenate reduction and pyrene metabolism.The identification of the alpha subunit of aromatic ring-hydroxylating dioxygenase (ARHD) gene, arsenate reductase gene (arsC), and arsenite transporter gene (ACR3(2)) supported the dual function of this isolate.Also the finding of the latter two genes indicated that this isolate possibly reduce As(V) via the known detoxification mechanism.This is the first report on obtaining an isolate which can simultaneously degrade PAHs and reduce arsenic, and the isolate is a potential candidate for bioremediation of soils contaminated by PAHs and arsenic, especially in conjunction with arsenic hyperaccumulator