Mechanism of resistance focusing on copper, mercury and arsenic in extremophilic organisms, how acidophiles and thermophiles cope with these metals

Extremophiles usually live in environment that are naturally higher in metal concentrations, either because they naturally live in acid environments where metal solubility is higher than neutrophilic environments or come from bioleaching/biooxidation processes or are present in hot springs that can contain metals from geological origin. Extremophiles possess many systems that are common to all microbes to resist metal toxicity, but a lot remains unknown and to be discovered. In this chapter the known mechanism by which they are able to resist metal toxicity will be covered, it will mostly focus on resistance to copper, mercury and arsenic in acidophilic and thermophilic microbes. These organisms easily adapt to their natural environment so they can successfully thrive under extreme conditions. Up to date, researcher have clearly showed that lateral gene transfer has occurred in acidophilic communities, in which these genomic islands encode for a number of metal resistances and different strains from the same microbe possess different capabilities to resist metals. The main mechanisms covered in this chapter are thiol-protective system (low molecular weight thiol buffers), none thiol complexation mechanism (nanoparticles and polyphosphates), enzymatic detoxification and efflux pumps.