Pseudomonas Arsenicoxydans

Pseudomonas Arsenicoxydans was isolated from the soil of the Appomattox River. It was first discovered in sediment samples from the Atacama Desert in Chile, which has a high arsenic concentration in both the water and sediments (Campos et al. 2010).


Campos V, Valenzuela C, Yarza P, Kampfer P, Vidal R, Zaror C, Mondaca M, Lopez-Lopez A, Rossello-Mora R. Pseudomonas arsenicoxydans sp nov., an arsenite-oxidizing strain isolated from the Atacama desert. Systematic and Applied Microbiology. 2010;33:193-197.

Date Collected: February 8, 2017

Methods for isolation and identification:

  • A soil sample was taken where the shore met the water at the Appomattox River (Figure 1). 100μl of the sample was put on an agar plate and was incubated at 25 degrees Celsius for 48 hours.
  • A light yellow-greenish, circular colony (Figure 2) was chosen for 16s rRNA gene sequencing by PCR amplification.
  • The PCR product was sent for DNA sequencing to identify the unknown bacteria of the colony selected.


Figure 1. Site of collection.


Figure 2. Colony from the Appomattox River sample selected for identification.


  • MspI digestion (Figure 3): Bands can be seen at the 1550, 600, and 500 marker.


Figure 3. Results of PCR amplification and MspI digestion for Appomattox River.

  • DNA Sequence: The sequenced PCR product produced 862 quality base pairs that were used to identify the bacteria as Pseudomonas Arsenicoxydans. Here is the link to the full sequence: NCBI BLAST revealed 98% similarity with 3 gaps out of 862 base pairs (Figure 4).


Figure 4. BLAST Alignment of Pseudomonas Arsenicoxydans.

Contributed by: Andrea Soles, BIOL 250, Spring 2017