Propionibacteria - Leha Vorobjeva - Google Books

https://books.google.de/books?id=vqVN-BcBhygC&pg=PA161#v=onepage

In a sense, propionic acid bacteria are domesticated bacteria. They might have been used for cheese making as early as 9000 years Be. In the last 40 years their pmctical uses have expanded to include vitamin B12 and propionic acid production, bread baking,…