Arsenite and Arsenate Metabolism of Sinorhizobium sp. M14 Living in the Extreme Environment of the Zloty Stok Gold Mine

Abstract

A new arsenite-oxidizing bacterium has been isolated from the arsenic-rich bottom sediments of a gold mine. This strain, designated M14 and identified as a Sinorhizobium species, is able to grow efficiently in extremely high concentrations of arsenate (up to 250 mM) and arsenite (up to 20 mM). Our studies of this psychrotolerant Sinorhizobium isolate revealed that it utilizes two mechanisms to adapt to the high concentrations of arsenic occurring in the mine. It is able to reduce arsenate to arsenite by means of the Ars system (detoxification only) and can simultaneously oxidize arsenite in a respiratory process, which generates energy for growth.

Keywords:

• gold mine
• arsenic
• arsenite oxidation
• Sinorhizobium