Microbes and metals: interactions in the environment

Research on the behaviour of microorganisms in geogenic or anthropogenic metallomorphic environments is an integral part of geomicrobiology. The investigation of microbial impact on the fate of minerals and geologically significant compounds of mining areas can lead to an understanding of biogeochemical cycles. Metabolic processes of microorganisms are the cause for the dissolution of minerals, and especially pyrite oxidation results in the generation of acid mine drainage which, in turn, leads to heavy metal contamination as a result of mining activities. On the other hand, microbial metabolism can also contribute to the formation of certain ore deposits over geological time. The adaptation to heavy metal rich environments is resulting in microorgansims which show activities for biosorption, bioprecipitation, extracellular sequestration, transport mechanisms, and/or chelation. Such resistance mechanisms are the basis for the use of microorganisms in bioremediation approaches. As only a small part of the worldwide occurring prokaryotes has been described yet, the understanding of the role bacteria play in a geogenic and pedogenic context is very likely to change deeply as soon as more habitat relevant microbial functions can be described. Examples for the identification of microbial processes from case studies may help to advance this field. The strongly interdisciplinary field of bio-geo-interactions spanning from the microorganism to the mineral holds much promise for future developments in both basic research as well as applied sciences.