Effects of proteases on L-glutamic acid fermentation

Area of Science:

• Biotechnology
• Industrial Microbiology
• Biochemical Engineering

Background:

• Proteins produced during L-glutamic acid fermentation can hinder bacterial growth and reduce efficiency.
• Undegraded proteins cause increased foaming, lower dissolved oxygen levels, and decreased overall fermentation yield.
• These issues necessitate strategies to improve protein utilization and fermentation performance.

Purpose of the Study:

• To investigate the impact of protease addition on L-glutamic acid fermentation.
• To determine the optimal protease type and concentration for enhanced fermentation outcomes.
• To improve L-glutamic acid yield and glucose conversion efficiency.

Main Methods:

• Protease, specifically trypsin, was added to the fermentation broth at a concentration of 0.5 g/L.
• The fermentation process was monitored for changes in protein decomposition, foam production, and dissolved oxygen levels.
• L-glutamic acid production and glucose conversion rates were compared against a control fermentation without protease addition.

Main Results:

• Addition of 0.5 g/L trypsin led to the decomposition and utilization of proteins by bacteria.
• Trypsin addition resulted in a 14.9% increase in final L-glutamic acid production (177.0 g/L vs. 154.0 g/L).
• The glucose conversion rate improved by 4.0% compared to the control (68.3% vs. 65.6%).

Conclusions:

• Protease treatment, particularly with trypsin, is an effective strategy to enhance L-glutamic acid fermentation.
• Decomposition of proteins by proteases improves substrate availability for bacteria, leading to higher yields.
• This approach offers a viable method to increase the efficiency and productivity of industrial L-glutamic acid fermentation.