Characterization of polycyclic aromatic hydrocarbons degradation and arsenate reduction by a versatile Pseudomonas isolate

• The versatile Pseudomonas isolate PAHAs-1 was isolated and characterized.
• The isolate could reduce As(V) and degrade PAHs simultaneously and independently.
• The presence of related functional genes confirmed versatilities of the isolate.
• PAHAs-1 represents the first example of As(V)-reducing and PAH-degrading isolate.

A Pseudomonas isolate, designated PAHAs-1, was found capable of reducing arsenate and degrading polycyclic aromatic hydrocarbons (PAHs) independently and simultaneously. This isolate completely reduced 1.5 mM arsenate within 48 h and removed approximately 100% and 50% of 60 mg l−1 phenanthrene and 20 mg l−1 pyrene within 60 h, respectively. Using PAHs as the sole carbon source, however, this isolate showed a slow arsenate reduction rate (4.62 μM h−1). The presence of arsenic affected cell growth and concurrent PAHs removal, depending on PAH species and arsenic concentration. Adding sodium lactate to the medium greatly enhanced the arsenate reduction and pyrene metabolism. The presence of the alpha subunit of the aromatic ring-hydroxylating dioxygenase (ARHD) gene, arsenate reductase (arsC) and arsenite transporter (ACR3(2)) genes supported the dual function of the isolate. The finding of latter two genes indicated that PAHAs-1 possibly reduced arsenate via the known detoxification mechanism. Preliminary data from hydroponic experiment showed that PAHAs-1 degraded the majority of phenanthrene (>60%) and enhanced arsenic uptake by Pteris vittata L. (from 246.7 to 1187.4 mg kg−1 As in the fronds). The versatile isolate PAHAs-1 may have potentials in improving the bioremediation of PAHs and arsenic co-contamination using the plant-microbe integrated strategy.