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Magnetite Biomineralization in Magnetospirillum gryphiswaldense: Time-Resolved Magnetic and Structural Studies

Magnetotactic bacteria biosynthesize magnetite nanoparticles of high structural and chemical purity that allow them to orientate in the geomagnetic field. This work presents a magnetic and structural time-resolved study on magnetotactic bacteria Magnetospirillum gryphiswaldensestrain MSR-1, to follow the process of biomineralization of magnetite nanoparticles. ACS Nano, 2013, 7 (4), pp 3297–3305

The biologically controlled formation of inorganic compounds is called biominerization. This process occurs in all organisms, from bacteria to humans. In one particular case, magnetotactic bacteria are able to mineralize magnetite nanocrystals with high chemical purity, species-specific crystal morphology on shape and size, and narrow size distribution. The structural study by means of Fe K-edge X-ray absorption near edge structure (XANES) and high-resolution transmission electron microscopy (HRTEM) allowed to identify two Fe phases present in the bacteria: ferrihydrite with a similar structure and high phosphours content as that of baterial ferritin cores, and magnetite. This confirm the role of ferryhydrite as a source of Fe for the magnetite biomineralization.
In addition, the quantification of the mass of each phase at specific times after Fe incubation, lead to distinguishing two

steps in the biomineralization process: the first, in which Fe is accumulated in the form of ferrihydrite, and the second, in which the magnetite is rapidly biomineralized from ferrihydrite. The XANES analysis also suggests that the origin of the ferrihydrite could be at bacterial ferritin cores, characterized by a poorly crystalline structure and high phosphorus content.

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Magnetite Biomineralization in Magnetospirillum gryphiswaldense: Time-Resolved Magnetic and Structural Studies
M. Luisa Fdez-Gubieda, Alicia Muela, Javier Alonso, Ana Garcia-Prieto, Luca Olivi, Rodrigo Fernandez-Pacheco and Jose Manuel Barandiaran.
ACS Nano, 2013, 7 (4), pp 3297–3305

Ultima modifica il Lunedì, 30 Giugno 2014 12:07