Characterization of the extremely arsenic-resistant Brevibacterium linens strain AE038-8 isolated from contaminated groundwater in Tucumán, Argentina

• Brevibacterium linens AE038-8 isolated from As-contaminated groundwater is highly resistant to arsenic oxyanions.
• B. linens AE038-8 is capable to reduce As(V) to As(III) in a complex medium.
• Several copies of ACR3 and arsC in the genome are proposed to be responsible for the tolerance mechanism in this strain.

Brevibacterium linens AE038-8, isolated from As-contaminated groundwater in Tucumán (Argentina), is highly resistant to arsenic oxyanions, being able to tolerate up to 1 M As(V) and 75 mM As(III) in a complex medium. Strain AE038-8 was also able to reduce As(V) to As(III) when grown in complex medium but paradoxically it could not do this in a defined minimal medium with sodium acetate and ammonium sulfate as carbon and nitrogen sources, respectively. No oxidation of As(III) to As(V) was observed under any conditions. Three copies of the ars operon comprising arsenic resistance genes were found on B. linens AE038-8 genome. In addition to the well known arsC, ACR3 and arsR, two copies of the arsO gene of unknown function were detected.