Other Projects

Life style and cell architecture of Achromatium

Achromatium is a large sulfur-oxidizing bacterium with a fascinating cell architecture. Most of the cell body is filled with calcium carbonate (i. e. calcite) and apparently only little space remains for other cellular parts, such as periplasm, cytoplasm and biological structures therein. We are currently working on localizing these cellular parts using different techniques in light and electron microscopy (fluorescence stainings and confocal microscopy, scanning and transmission electron microscopy).

We also investigate aspects of the life style of Achromatium in aquatic sediments. As gradient organisms, these cells thrive within opposing gradients of oxygen and sulfide. With chemotaxis assays we study the effect of oxidizing and reducing agents on the motility of Achromatium. In a recent study we found that despite being full of calcite, Achromatium cells are subjected to grazing and parasitism.

Achromatium cells appear white in front of a black background due to light reflection by multiple calcite bodies (a) that fill most of the cell volume (b). The biological role of intracellular calcite deposition is still unknown. Image from Schorn & Cypionka Microb Ecol (2018) 76: 584-587
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