New high-density fermentation method for producing high molecular weight polysialic acid based on the combination...

Area of Science:

• Biotechnology
• Microbial Fermentation
• Biopolymer Production

Background:

• Polysialic acid (PSA), a linear amino polysaccharide, has vast application potential but is limited by its low molecular weight.
• Current microbial fermentation methods struggle to achieve high molecular weight PSA, hindering its industrial scalability.

Purpose of the Study:

• To develop a novel fermentation strategy for producing high molecular weight polysialic acid (PSA).
• To enhance both the molecular weight and yield of PSA through a combined fermentation approach.

Main Methods:

• Utilized Escherichia coli K235 6E61 as the fermentation strain.
• Implemented a three-phase control strategy involving pH, mixing speed, and addition of exogenous substances (Na5P3O10 and n-hexadecane).
• Optimized air flow at 1.2 vvm throughout the 36-hour fermentation process.

Main Results:

• Achieved a record high molecular weight of 498 kDa for PSA at 32 hours, the highest reported for microbial fermentation.
• Obtained a PSA yield of 6.27 g·L⁻¹, representing the highest yield from natural bacteria to date.
• Demonstrated that the combined fermentation strategy significantly enhances PSA molecular weight and yield.

Conclusions:

• The developed combination fermentation strategy is highly effective for simultaneously increasing PSA molecular weight and yield.
• This approach holds significant importance for the industrial production of high molecular weight PSA.
• The study presents a breakthrough in microbial production of high-value biopolymers.