Volutin granules are an intracytoplasmic storage form of complexed

inorganic An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds⁠that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemistry''. Inor ...

polyphosphate A polyphosphate is a Salt (chemistry), salt or ester of polymeric oxyanions formed from tetrahedral PO4 (phosphate) structural units linked together by sharing oxygen atoms. Polyphosphates can adopt linear or a cyclic (also called, ring) structure ...

, the production of which is used as one of the identifying criteria when attempting to isolate ''

Corynebacterium diphtheriae ''Corynebacterium diphtheriae'' is a Gram-positive pathogenic bacterium that causes diphtheria. It is also known as the Klebs–Löffler bacillus because it was discovered in 1884 by German bacteriologists Edwin Klebs (1834–1912) and Friedrich ...

'' on

Löffler's medium Löffler's medium is a special substance used to grow diphtheria bacilli to confirm the diagnosis. History In 1887, Friedrich Loeffler devised a culture medium containing horse serum, meat infusion, and dextrose for use in the cultivation of c ...

. Polyphosphate granules display the

metachromatic {{inline citations needed, date=November 2024 Metachromasia (var. metachromasy) is a characteristic change in the color of staining carried out in biological tissues, exhibited by certain dyes when they bind to particular substances present in th ...

effect, appearing red when stained with

methylene blue Methylthioninium chloride, commonly called methylene blue, is a salt used as a dye and as a medication. As a medication, it is mainly used to treat methemoglobinemia. It has previously been used for treating cyanide poisoning and urinary trac ...

. Volutin granules can also be found in the cytoplasm of ''

Saccharomyces ''Saccharomyces'' is a genus of fungi that includes many species of yeasts. ''Saccharomyces'' is from Greek σάκχαρον (sugar) and μύκης (fungus) and means ''sugar fungus''. Many members of this genus are considered very important in f ...

'', a genus of

ascomycete Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 64,000 species. The def ...

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

.Willey, J. M., Sherwood, L. M. and Woolverton, C. J. (2011). Prescott's Microbiology, 8th Ed. McGraw Hill They are characteristic for different species and depend on the age and condition of the culture. Volutin granules (metachromatic or Babes-Ernst granules) are highly refractive, strongly basophilic bodies consisting of polymetaphosphate. The eponymous name was given in honour of the discoverers Paul Ernst and Victor Babes. They appear reddish when stained with polychrome methylene blue or

toluidine blue Toluidine blue, also known as TBO or tolonium chloride (INN) is a blue cationic (basic) dye used in histology (as the toluidine blue stain) and sometimes clinically. Test for lignin Toluidine blue solution is used in testing for lignin, a compl ...

(metachromasia). Special staining techniques such as Albert's or Neisser's demonstrate the granules more clearly. Volutin granules are characteristically present in diphtheria bacilli. Their function is uncertain. They have been considered to represent a reserve of energy and phosphate for cell metabolism but they are most frequent in cells grown under conditions of nutritional deficiency and tend to disappear when the deficient nutrients are supplied.

References

Cell anatomy {{Microbiology-stub