费氏丙酸杆菌(Propionibacterium freudenreichii)。所生产的二氧化碳制造瑞士奶酪中的孔。此外，瑞士奶酪中的特殊口味，是由于该细菌从葡萄糖所产生的丙酸而造成的。

这种细菌的其他用途包括制造丙酸和维他命B12，此外，它也是一种益生菌。

Propionibacterium freudenreichii is a Gram-positive, non-motile bacterium that plays an important role in the creation of Emmental cheese, and to some extent, Jarlsberg cheese, Leerdammer and Maasdam cheese. Its concentration in Swiss-type cheeses is higher than in any other cheese. Propionibacteria are commonly found in milk and dairy products, though they have also been extracted from soil. P. freudenreichii has a circular chromosome about 2.5 Mb long. When Emmental cheese is being produced, P. freudenreichii ferments lactate to form acetate, propionate, and carbon dioxide (3 C₃H₆O₃ → 2 C₂H₅CO₂ + C₂H₃O₂ + CO₂).