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Isolation and Characterization of a Psychrotolerant Arsenite-Oxidizing Bacterium from a Gold Mine in Zloty Stok, Poland

Microbial activities play a significant role in a global cycle of arsenic. Some microbes can catalyze redox reactions with arsenic species what helps them to obtain energy for metabolic growth. A few aerobic chemolithoautotrophic species can derive metabolic energy from the oxidation of arsenite [As(III)]. Anaerobic respiration of arsenate [As(V)] is also carried out by some species of Bacteria and Archaea. This report describes a new psychrotolerant bacterium, isolated from a gold mine in Zloty Stok, which is able to efficiently oxidize As(III) into As(V). This strain, designed M-14, can grow chemolithoautrophically using arsenite as a source of energy. The generation time for growth on arsenite [5mM As(III)] as the electron donor, oxygen as the electron acceptor, and carbon dioxide (CO2) as the carbon source, was 9 h. The rate of arsenic transformation depends on the cell density, addition of trace amounts of organic matter and temperature of culture. The most effective arsenite oxidation was on minimal medium with arsenite (5 mM) and yeast extract (0.04 %) at room temperature (22 oC), but As(III) oxidation was also observed at 10 oC. Besides chemolithoautotrophic growth, strain M14 also grew in minimal medium containing the following carbon and energy sources: acetate, lactate, succinate, mannitol, sucrose, glucose, arabinose, fructose, trehalose, maltose, xylose, or galactose. Tolerance to As(III) and As(V) was also tested and strain M14 showed hyper tolerance to both inorganic arsenic species. Analysis of the 16S rRNA gene sequence revealed that strain M-14 is a member of Rhizobium/Agrobacterium branch of the Alphaproteobacteria. This strain shows high similarity values (98.9 99%) with Sinorhizobium species. Advanced Materials Research Online: 2007-07-15 ISSN: 1662-8985, Vols. 20-21, pp 575-575 doi:10.4028/www.scientific.net/AMR.20-21.575 © 2007 Trans Tech Publications Ltd, Switzerland