63 / 2025-03-30 20:30:05

The Mechanisms of Magnetosome Biomineralization and Chain Organization in Magnetotactic Bacteria

Magnetotactic Bacteria,Biomineralization,magnetosome

Theme 5: Life-Mineral Interaction and Evolutions > Session 5a: Microbe-mineral Interactions and Their Biosignatures: Integrating Laboratory Data with Field Insights

Biomineralization is a widespread phenomenon in nature, occurring in organisms ranging from bacteria to complex animals. A remarkable example of bacterial-controlled biomineralization is the formation of magnetic nanoparticles (Fe₃O₄ or Fe₃S₄) within membrane-bound magnetosomes in magnetotactic bacteria (MTB). These magnetosomes are often arranged into chains, acting as a biological “compass needle” that enables MTB to navigate along geomagnetic field lines and locate optimal microenvironments for growth. Despite the diversity of magnetosome morphologies and chain configurations observed in MTB, the mechanisms underlying their biomineralization and organization remain poorly understood. Here, we first investigate the molecular basis of magnetosome formation and chain organization in the model MTB strain Magnetosprium magneticum AMB-1 (AMB-1), which belong to the Alphaproteobacteria class and produce cuboctahedron-shaped magnetite. Through genetic analysis and cryo-electron tomography, we identified key genes (mamE, mamM, mamO, and mamD) essential for magnetosome membrane growth regulation and magnetite crystal nucleation. Additionally, we discovered that mcaA and McaB regulate chain organization; their deletion transforms fragmented magnetic crystals into a continuous midcell chain. Leveraging these insights, we engineered a folded magnetosome chain and combined it with micromagnetic simulations to analyze a natural magnetofossil sample. Beyond AMB-1, we are also exploring the metabolic and biomineralization mechanisms of Nitrospirota MTB, which produce hundreds of bullet-shaped magnetosomes per cell ^1-3. These findings advance our understanding of diverse MTB biomineralization strategies and highlight their ecological significance in natural environments.



References

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