Development of an industrializable fermentation process for propionic acid production.

Area of Science:

• Biotechnology
• Industrial Microbiology
• Chemical Engineering

Background:

• Propionic acid (PA) is a versatile short-chain fatty acid with significant industrial applications.
• Current petrochemical production routes for PA face challenges related to price volatility and feedstock availability.
• Developing a renewable, cost-effective production method for PA is crucial for sustainable chemical manufacturing.

Purpose of the Study:

• To engineer an industrially feasible and renewable fermentation process for propionic acid (PA) production.
• To optimize microbial strains and fermentation conditions for enhanced PA yield and productivity.
• To reduce production costs by utilizing industrial-grade feedstocks.

Main Methods:

• Screening of seventeen Propionibacterium strains to identify the optimal platform strain for PA fermentation.
• Optimization of fermentation parameters, including inoculum density, headspace pressure, and shear, to maximize productivity and minimize byproducts.
• Transitioning from lab-grade media to industrial feedstocks, such as enzymatically treated corn mash (ECM), with supplementation as needed.

Main Results:

• Propionibacterium acidipropionici ATCC 4875 was selected as the platform strain.
• Fermentation productivity was tripled to over 2 g/l/h through inoculum densification.
• Optimized ECM medium with cyanocobalamin supplementation achieved 0.5 g/l/h productivity and 0.60 g/g PA yield at a cost below $1/kg PA.

Conclusions:

• The developed fermentation process significantly improves the economic viability of bio-based propionic acid production.
• This renewable route offers a competitive alternative to traditional petrochemical manufacturing of PA.
• Further optimization can bridge the gap between bio-based and petrochemical production costs for PA.