Pediococcus acidilactici
Also known as P. acidilactici, Pediococcus cerevisiae (historical)
The fast, heat-loving acidifier of American-style fermented sausage, historically the very first commercial meat starter, and a maker of the anti-Listeria bacteriocin pediocin.
Pediococcus acidilactici carries its nature in its name: Pediococcus, from the Greek for a berry that divides across a plane, describes the way these round bacteria split in two directions to sit in neat squares of four, or tetrads, unlike the clusters of the staphylococci or the chains of other lactic bacteria; acidilactici means, plainly, of lactic acid. It is a Gram-positive, homofermentative lactic coccus, and its distinguishing trait for the curesmith is a love of heat.
It holds a particular place in history, for it was the first meat starter ever sold. When controlled fermentation began in 1955, the American culture, from Niven and Deibel, was a Pediococcus then called Pediococcus cerevisiae, later reclassified as Pediococcus acidilactici; it reached the market in 1957 under the name ACCEL and founded the warm, fast American school of sausage fermentation (the fuller story is under starter-culture). Where Europe fermented cool and slow with lactobacilli, America fermented warm and quick with this pediococcus.
Its work is the lactic bacterium's usual task, turning sugar to lactic acid to set the tang and secure the sausage against spoilage and pathogens, but it does it fast and hard, and above all it does it at high temperature, which suits a product made and eaten quickly rather than aged for months. Commercial fast cultures built around it, such as the well-known Bactoferm LHP, are aimed squarely at fermentation temperatures of roughly 26 to 38 degrees Celsius, that is 80 to 100 Fahrenheit. Many strains also produce pediocin, one of the most effective natural bacteriocins against Listeria, so the organism protects even as it acidifies.
In use it belongs to the warm, quick, American tradition of summer sausage, snack sticks and semi-dry products, paired as ever with a colour-and-flavour staphylococcus. It is bought freeze-dried or frozen, rehydrated in unchlorinated water and mixed through the meat with ample sugar to fuel its brisk acid drop. Reach for it when a sharp, dependable tang is wanted in days; reach for a lactobacillus when a slow, cool, flavour-building ferment is the goal.