ENHANCED BACTERIOCIN PRODUCTION BY PROPIONIBACTERIUM-THOENII IN FED-BATCH FERMENTATION

Synthesis of the bacteriocin propionicin PLG-1 as well as culture grow th and organic acid production by Propionibacterium thoenii P127 were followed in fed-batch fermentations conducted for 504 h in a sodium la ctate broth. Average concentrations of viable cells were higher in two small-scale fed-batch fermentations than in batch fermentations: 2.2 x 10(9) cells per ml versus 3.7 x 10(8) cells per ml. Propionic acid c oncentration averaged 35.8 g/liter at the end of fed-batch fementation , and maximum bacteriocin titers were 184 and 146 AU/ml in the two fed -batch fermentations. After reaching the maximum value, bacteriocin ac tivity dropped sharply upon continued incubation. Large quantities of propionicin PLG-1 could be obtained in large-scale fed-batch fermentat ion, but the concentration (100 AU/ml) was lower than in the small-sca le fermentations. Fed-batch fermentation shows promise as a method to obtain high concentrations of bacteriocin from the propionibacteria.