Hybrid substrate-based pH autobuffering GABA fermentation by Levilactobacillus brevis CD0817.

Area of Science:

• Biotechnology
• Microbial Fermentation
• Biochemical Engineering

Background:

• Gamma-aminobutyric acid (GABA) is a bioactive substance with significant research interest.
• Existing GABA fermentation methods using single substrates (L-glutamic acid or L-monosodium glutamate) have limitations.
• Optimization of GABA production through microbial fermentation is crucial for its applications.

Purpose of the Study:

• To develop and evaluate a pH auto-buffering strategy for enhanced GABA fermentation.
• To optimize fermentation parameters for Levilactobacillus brevis CD0817 using this strategy.
• To validate the strategy's effectiveness in a larger-scale fermenter.

Main Methods:

• A pH auto-buffering strategy was devised using a mixture of L-glutamic acid and monosodium L-glutamate.
• Flask trials were conducted to optimize fermentation medium composition and temperature for Levilactobacillus brevis CD0817.
• Optimized parameters were validated in a 10 L fermenter.

Main Results:

• The optimal fermentation medium included specific concentrations of L-glutamic acid, monosodium L-glutamate, glucose, yeast extract, MnSO4·H2O, and Tween 80 at 30°C.
• In a 10 L fermenter, GABA production reached 353.1 ± 8.3 g/L after 48 hours.
• The pH auto-buffering strategy effectively maintained acidity essential for GABA fermentation, with the pH rising from 4.56 to 6.10.

Conclusions:

• The pH auto-buffering strategy using a substrate mixture is effective for improving GABA fermentation by Levilactobacillus brevis CD0817.
• This strategy offers a promising approach for enhancing GABA production in microbial fermentation processes.
• The method has the potential for broad application in other GABA fermentation studies.