ABSTRACT
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 °C for 10 days, but produced propionic acid at concentrations of 3265.32, 3670.76, and 1926.04 µg/mL at 25, 30, and 40 °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 µg/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.
