Enhanced Bacteriocin Production by Propionibacterium thoenii in Fed-Batch Fermentation ^‡

Area of Science:

• Microbiology
• Biotechnology
• Food Science

Background:

• Propionibacterium thaenii P127 produces the bacteriocin propionicin PLG-I.
• Bacteriocins are antimicrobial peptides with potential applications in food preservation and medicine.
• Optimizing fermentation processes is crucial for maximizing bacteriocin yield.

Purpose of the Study:

• To investigate the efficacy of fed-batch fermentation for propionicin PLG-I synthesis.
• To evaluate the impact of fed-batch fermentation on Propionibacterium thaenii P127 growth and organic acid production.
• To determine optimal conditions for high-concentration bacteriocin production.

Main Methods:

• Fed-batch fermentation of Propionibacterium thaenii P127 in sodium lactate broth for 504 hours.
• Monitoring of viable cell concentrations, propionic acid production, and bacteriocin titers.
• Comparison of small-scale and large-scale fed-batch fermentation performance.

Main Results:

• Fed-batch fermentation significantly increased viable cell concentrations compared to batch fermentation (2.2 × 10^9 cells/ml vs. 3.7 × 10^8 cells/ml).
• Average propionic acid concentration reached 35.8 g/liter.
• Maximum bacteriocin titers of 184 and 146 AU/ml were achieved in small-scale fed-batch fermentations.
• Large-scale fermentation yielded substantial quantities but at a lower concentration (100 AU/ml).

Conclusions:

• Fed-batch fermentation is a promising strategy for enhancing propionicin PLG-I production by Propionibacterium thaenii P127.
• Process optimization is needed to maintain high bacteriocin concentrations in large-scale production.
• Further research can explore applications of propionicin PLG-I in various industries.