Analysis of hemin effect on lactate reduction in Lactococcus lactis

Area of Science:

• Microbiology
• Biotechnology
• Industrial Fermentation

Background:

• Lactococcus lactis produces lactate, which inhibits its own growth.
• Hemin is known to suppress lactate production in L. lactis under aerobic conditions.
• Optimizing fermentation conditions is crucial for industrial applications of L. lactis.

Purpose of the Study:

• To investigate the optimal conditions for hemin's effect on reducing lactate production in L. lactis ATCC11454.
• To evaluate the impact of hemin on L. lactis growth and metabolic by-products.
• To explore the potential of microaerobic fed-batch culture for low lactate maintenance.

Main Methods:

• Culturing L. lactis ATCC11454 under various conditions with and without hemin.
• Comparing lactate production and bacterial growth in batch and fed-batch cultures.
• Analyzing metabolic shifts under microaerobic fed-batch conditions with hemin.

Main Results:

• Hemin addition improved L. lactis growth and reduced lactate production by 1.8-fold in batch and 1.3-fold in fed-batch cultures.
• Microaerobic fed-batch culture with hemin effectively suppressed lactate production.
• A metabolic shift from lactate to acetoin and acetate was observed under optimal conditions.
• Nisin production did not increase despite significant lactate reduction.

Conclusions:

• Hemin and microaerobic fed-batch culture are effective strategies for reducing lactate accumulation in L. lactis.
• These conditions promote bacterial growth and alter metabolic pathways.
• Further research may be needed to enhance nisin production concurrently with lactate reduction.