Berlin 2015 – scientific programme

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BP: Fachverband Biologische Physik

BP 13: Posters: Imaging and Superresolution Optical Microscopy

BP 13.5: Poster

Monday, March 16, 2015, 17:30–19:30, Poster A

Probing the intracellular pH in magnetotactic bacteria — •Erika Günther, Mathieu Bennet, and Damien Faivre — Max-Planck Institute of Colloids and Interfaces, Biomaterials, Potsdam, Germany

Magnetotactic bacteria are microorganisms that possess encapsulated biomineralised magnetite nanoparticles (magnetosomes) to navigate along the geomagnetic field lines. The formation of magnetite nanoparticles typically requires iron concentrations (200 µM) and pHs
(pH > 8) that are toxic to cells.
In order to understand how magnetotactic bacteria biomineralise iron nanoparticles in physiological conditions, we aim at measuring their intracellular chemical properties using ratiometric fluorescence microscopy and fluorescence lifetime imaging microscopy.
We have measured the intracellular pH in living Magnetospirillum gryphiswaldense MSR-1 cells using confocal laser scanning microscopy. From these measurements, we conclude that the biomineralisation of iron nanoparticles in MTB does not result in the presence of a non-physiological cytoplasmic pH. Magnetotactic bacteria buffer their intracellular pH to pH 7.0 ± 0.25 when exposed to a range of extracellular from pH 6.5 to pH 7.5. We will present the strategy that we are adopting to measure the chemical potential in the cytoplasm and discuss the possibility of better spatially resolving our measurements in order to gain insight into the chemical conditions in the magnetosomes.