Sequestration and mineralization of metals is a widespread phenomenon in the microbial world whose full environmental impact has yet to be understood. One particularly fascinating example of microbe-metal interactions is the uptake and transformation of metals within specialized subcellular compartments in bacteria. We study magnetotactic bacteria (MTB), organisms that use their magnetosome organelles to transform soluble iron into subcellular magnetic minerals (magnetite or greigite) that are used as an internal compass to navigate along geomagnetic fields. MTB are surprisingly ubiquitous in aquatic environments, are thought to represent the most ancient biomineralizaiton process, and are incredibly diverse in their genealogy and biomineralization behaviors. They are also great candidates for development of biomineralization based applications. Over the last few years we have identified many of the genes required for biomineralization in two model organisms, Magnetospirillum magneticum AMB-1 and Desulfovibrio magneticus RS-1. Through this work, we have discovered evolutionarily conserved pathways, as well as novel innovations, that define the magnetite biomineralization processes of diverse MTB. In the process of studying magnetite formation in RS-1, we discovered an independent organelle, called the ferrosome, which also sequesters iron within the cell. Surprisingly, the ferrosome appears to be widespread amongst many diverse bacterial species, raising the possibility that its activity can have an impact on the distribution of iron in various environments. These two systems, the magnetosome and the ferrosome, highlight the diversity of microbial-metal interactions and the variety of genetic and biochemical mechanisms that create organelles and minerals.

Biomineralization of metals in bacterial organelles

255th National Meeting (2018)

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