High cell density sequential batch fermentation for enhanced propionic acid production from glucose and...

Area of Science:

• Biotechnology
• Industrial Microbiology
• Metabolic Engineering

Background:

• Propionic acid (PA) fermentation from renewable resources faces challenges in volumetric productivity and product concentration, hindering industrial application.
• High cell density (HCD) fermentation techniques offer a solution to overcome these limitations.
• Utilizing agro-industrial by-products as nutrient sources is crucial for economic viability.

Purpose of the Study:

• To evaluate propionic acid (PA) production by Acidipropionibacterium acidipropionici using HCD batch fermentation with cell recycle.
• To assess the feasibility of using glucose and a crude glycerol/glucose mixture as carbon sources.
• To investigate the use of heat-treated potato juice (HTPJ) as a nitrogen source.

Main Methods:

• HCD batch fermentations with continuous cell recycling were employed.
• Fermentations were conducted using glucose or a crude glycerol/glucose mixture.
• Heat-treated potato juice (HTPJ) was utilized as the nitrogen source.

Main Results:

• Fermentation of 40 g/L glucose yielded an average of 18.76 g/L PA per batch with a maximum rate of 1.15 g/L/h and biomass of 39.89 gCDW/L.
• Co-fermentation of crude glycerol/glucose (60 g/L:30 g/L) produced an average of 35.36 g/L PA per batch at a rate of 0.35 g/L/h, reaching 12.66 gCDW/L biomass.
• Biotin supplementation enhanced cell growth and PA productivity but increased acetic acid by-product formation.

Conclusions:

• HCD batch fermentation with cell recycling is a promising strategy for industrial propionic acid production.
• The co-fermentation of crude glycerol and glucose, using industrial by-products, achieved high reported productivity.
• This approach enhances the industrial feasibility of microbial propionic acid production.