Process engineering towards an oxidative cellular state improves 3-hydroxypropionic acid production with...

Area of Science:

• Biotechnology and Bioengineering
• Metabolic Engineering
• Industrial Microbiology

Background:

• 3-hydroxypropionic acid (3-HP) is a key bio-based platform chemical derived from renewable resources.
• Crude glycerol, a byproduct of biodiesel production, is a sustainable feedstock for microbial fermentation.
• Lentilactobacillus diolivorans shows promise for converting glycerol to 3-HP, but process optimization is needed.

Purpose of the Study:

• To engineer Lentilactobacillus diolivorans for improved 3-hydroxypropionic acid (3-HP) production.
• To optimize fermentation conditions, specifically cellular redox balance, for enhanced 3-HP titers.
• To investigate the impact of oxygen and glucose availability on 3-HP biosynthesis.

Main Methods:

• Utilized an established fed-batch fermentation process as a baseline.
• Modulated cellular redox state by adjusting oxygen supply and glucose-to-glycerol ratio in the feed medium.
• Cultivated Lentilactobacillus diolivorans under optimized conditions for 180 hours.

Main Results:

• Individual adjustments in oxygen availability and glucose/glycerol ratio improved 3-HP production.
• Combined optimization of 30% O2 and a glucose/glycerol ratio of 0.025 mol/mol resulted in a 3-HP titer of 67.7 g/L.
• This represents the highest reported 3-HP titer achieved using Lactobacillus species.

Conclusions:

• Modulating cellular redox balance through controlled oxygen and substrate feeding is crucial for enhancing 3-HP production.
• The engineered Lentilactobacillus diolivorans strain and optimized process demonstrate a highly efficient route for bio-based 3-HP.
• This study sets a new benchmark for 3-HP production, paving the way for sustainable chemical manufacturing.