Growth characterization of Propionibacterium and propionic acid production capabilities at different temperatures and pH levels

Bacteria from the Propionibacterium genus were cocktailed to investigate growth and production of propionic acid at different temperatures and pH levels. A gas chromatograph with a flame ionization detector was also used for instrumental analysis. The Propionibacterium cocktails did not produce propionic acid at 10 and 20 degrees C for 10 days, but produced propionic acid at concentrations of 3265.32, 3670.76, and 1926.04 mu g/mL at 25, 30, and 40 degrees C for 18 days, respectively. In pH tests, the cocktails did not produce propionic acid at pH 3 and 9 for 14 and 7 days, respectively. However, they produced propionic acid at concentrations of 2596.66, 2952.66, 3321.35, and 3586.95 mu g/mL at pH 4, 5, 6, and 7 for 18 days, respectively. Growth characteristics of Propionibacterium cocktails by temperature and pH were set so that they reached the extinction stage after four days in the logarithmic phase.