Magnetotactic bacteria accumulate a large pool of iron distinct from their magnetite crystals.

Magnetotactic bacteria accumulate a large pool of iron distinct from their magnetite crystals. Appl Environ Microbiol. 2020 Sep 04;: Authors: Amor M, Ceballos A, Wan J, Simon CP, Aron AT, Chang CJ, Hellman F, Komeili A Abstract Magnetotactic bacteria (MTB) are ubiquitous aquatic microorganisms that form intracellular nanoparticles of magnetite (Fe3O4) or greigite (Fe3S4) in a genetically controlled manner. Magnetite and greigite synthesis requires MTB to transport a large amount of iron from the environment. Most intracellular iron was proposed to be contained within the crystals. However, recent mass spectrometry studies suggest that MTB may contain a large amount of iron that is not precipitated in crystals. Here, we attempt to resolve these discrepancies by performing chemical and magnetic assays to quantify the different iron pools in the magnetite-forming strain Magnetospirillum magneticum AMB-1, as well as mutant strains showing defects in crystal precipitation, cultivated at varying iron concentrations. All results show that magnetite represents at most 30 % of the total intracellular iron under our experimental conditions, and even less in the mutant strains. We further examined the iron speciation and subcellular localization in AMB-1 using the fluorescent indicator FIP-1 that is designed for detection of labile Fe(II). Staining with this probe suggests that unmineralized reduced iron is found in the cytoplasm and associated...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Tags: Appl Environ Microbiol Source Type: research