Linking genotype and phenotype in an economically viable propionic acid biosynthesis process.

Area of Science:

• Biotechnology
• Metabolic Engineering
• Microbial Fermentation

Background:

• Propionic acid (PA) is a vital chemical used in food preservation and monomer synthesis.
• Current production relies on the ethylene hydrocarboxylation 'oxo-process'.
• Biological production by *Propionibacterium* species is promising but requires yields >0.6 g/g for competitiveness.

Purpose of the Study:

• To develop a microbial strain for high-yield propionic acid (PA) production.
• To elucidate the genetic and metabolic underpinnings of enhanced PA yield.
• To establish an economically viable bioprocess for PA manufacturing.

Main Methods:

• Genome shuffling was employed to generate a high-performance PA-producing strain.
• Multi-omics analyses (genomics, metabolomics, transcriptomics) were conducted for strain characterization.
• A feeding strategy was implemented to optimize the bioprocess and product yield.

Main Results:

• A novel strain achieved propionic acid yields exceeding the 0.6 g/g threshold.
• Key mutations identified: enhanced sucrose transporter, improved amino acid transporter, and a cytochrome C biogenesis gene mutation linked to ATP production via the Wood-Werkman cycle.
• The optimized bioprocess reached a product concentration of 70 g/L.

Conclusions:

• Genome shuffling successfully created a *Propionibacterium* strain with commercially relevant PA yields.
• Multi-omics data revealed metabolic shifts including upregulated amino acid pathways and altered sugar metabolism.
• The study highlights the potential of engineered microbial fermentation to surpass conventional chemical synthesis for PA production, with projected economic advantages.