Volutin granules


Volutin granules are an intracytoplasmic storage form of complexed inorganic polyphosphate, the production of which is used as one of the identifying criteria when attempting to isolate Corynebacterium diphtheriae on Löffler's medium. Polyphosphate granules display the metachromatic effect, appearing red when stained with methylene blue.
They can also be found in the cytoplasm of Saccharomyces, a genus of ascomycete fungi.