The Biofilm Lifestyle of Acidophilic Metal/Sulfur-Oxidizing Microorganisms.

Abstract

The most common and widespread lifestyle of microbes on earth is in form of biofilms. These are communities of different species of microorganisms embedded in amatrix of extracellular polymeric substances (EPS), which mainly consist of polysaccharides,proteins, nucleic acids and lipophilic compounds. Biofi lms can befound as surface-associated or “fl oating mats”, occurring in air-water interfaces.The biofi lm lifestyle protects cells from environmental stress like desiccation, nutrient starvation, radiation and/or oxidative stress (Flemming and Wingender 2010 ). Bioleaching of metal sulfi des (MS) like pyrite (FeS 2 ) or chalcopyrite (CuFeS 2 ) is accelerated by a diverse group of acidophilic metal/sulfur-oxidizing microorganisms(AMOM). These can effect MS dissolution through the oxidation of iron(II)- ions and/or reduced inorganic sulfur compounds (RISCs). Thereby iron(III)-ions