Propionibacterium freudenreichii

Propionibacterium freudenreichii was first discovered and isolated in the early 20th century by Eduard von Freudenreich and Sigurd Orla-Jensen. They discovered the bacterium while studying propionic acid fermentation in Emmental cheese. Its genus is named after propionic acid, which this bacterium produces. The species freudenreichii is named after von Freudenreich. == Features of the bacterium ==

The cells themselves most commonly take the shape of pleomorphic (able to assume different forms) rods (0.2–1.5 micrometers *, 1–5 micrometers) but they can also be coccoid, bifid, branched, or filamentous. The length of the cell can be as long as 20 micrometers. When grown on solid media the colonies formed can appear smooth, convex, or rough. When grown in liquid media the colonies may be observed, appearing granular and varying in size. The colonies can vary quite a bit in color: they have been observed as being red, pink, orange, yellow, gray, and white. P. freudenreichii is gram-positive and non-motile. One discernible feature of this bacterium is that it produces large quantities of propionic and acetic acids. It can ferment sugars and polyhydroxy alcohols, and lactate provided that there are bacteria nearby are producing it by their own fermentative activities (this is known as secondary fermentation). It can also produce iso-valeric, formic, succinic, or lactic acids as well as carbon dioxide (although these are all secreted in lesser amounts than the other substances it produces). The value of P. freudenreichii's DNA coding is 2,321,778 bp (87.64% of the genome). The genome itself is circular in shape. Its genome has one finalized chromosome with no plasmids. The genome is 2,649,166 nucleotides in size. The G/C content of the genome is 67.34%. == Cheesemaking ==

Propionibacterium freudenreichii is perhaps best known for its usages in the production of cheeses, most notably Swiss cheese. == Probiotic uses ==

One area of intrigue surrounding this bacterium has been its potential usage as a probiotic. P. freudenreichii produces a bifidogenetic compound that aids in stimulating bifidobacterial growth. On the molecular level, recent studies have indicated that the surface proteins of P. freudenreichii adhere to human intestinal cells. This binding of surface proteins is what allows for certain functions to then take place, such as modulating the release of cytokines by human intestinal cells. == References ==