One of the most intriguing examples for biogenic magnetic nanoparticles (MNPs) is found in magnetotactic bacteria (MTB). MTB synthesize intracellular, enveloped crystals of magnetite (Fe3O4) called magnetosomes, which are formed by a process called biologically-controlled mineralization (BCM). Because of unique features, BCM of magnetosomes has been in the focus of strong interdisciplinary interest to understand bacterial control on MNPs formation. However, little is known about how BCM occurs at the bioche mical and molecular level. Consequently, the reaction pathway for magnetite formation remains to be elucidated. The objective of our research is therefore to elucidate the BCM process of MNPs formation in MTB. We aim understanding the physico-chemical conditions governing MNPs formation within the magnetosomes, and the role of biological molecules involved in interactions at the organic-inorganic interface. Such an objective will imply in vivo microbiological experiments with bacteria, and in vitro biomimetic experiments including biomolecules to mimic in situ conditions.
These biomolecules are expected to affect reaction kinetics, and geochemical properties of the crystals when compared to purely inorganic synthesis.
This requires an integrated approach involving interactions between microbiologists headed by Dr. SchÃ¼ler (the researcher) and a geochemist (Dr. Faivre, the research fellow) to tackle the problem of biogenic MNPs formation. Thus, we will acquire a detailed knowledge of the reaction pathway. T his will provide a tool to discriminate between biogenic and inorganic magnetite nanocrystals. This is relevant for the debate about a possible fossilized trace of life on ALH84001 meteorite. Moreover, this will significantly improve our knowledge on the control of MNPs in vitro synthesis, which in turn will be of immediate relevance for the biomimetic production of advanced materials with tailored magnetic and crystalline characteristics.
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