Studies on bacteriocin (thermophilin T) production by Streptococcus thermophilus ACA-DC 0040 in batch and fed-batch fermentation modes.

Growth conditions that support bacteriocin (thermophilin T) production by Streptococcus thermophilus ACA-DC 0040 were identified. Synthesis of thermophilin T occurred during primary metabolic growth, while its specific rate of synthesis seemed to be optimal at T = 30 degrees C. Thermophilin T activity rapidly decreased in the stationary phase, especially at high growth temperature (i.e. T = 42 degrees C). In media with high content of complex nitrogen sources, high amounts of bacteriocin were detected in the growth environment, while about an 8-fold increase of thermophilin T titer and a 2-fold increase of specific synthesis rate was achieved when a fed-batch fermentation mode was applied.