An efficient and large-scale preparation process for polysialic acid by Escherichia coli CCTCC M208088

Polysialic acid (PSA) is a novel pharmaceutical material used in control release for protein drugs or in biomedical applications as scaffold. An efficient pilot production process for bacterial PSA was developed. Our PSA fermentation process by Escherichia coli CCTCC M208088 was optimized in a 500 L fermenter using a novel strategy by controlling pH with ammonia water feeding coupled with sorbitol supplementation. The resulting PSA level increased to 5500 mg/L as compared with the 1500 mg/L of the control. Furthermore, the process for the PSA purification from the fermentation broth was also established. PSA was isolated from the broth by ethanol precipitation, filtration with perlite as filter aid, followed by cetyl pyridinium chloride (CPC) precipitation and lyophilization. The final PSA product obtained had 98.1 ± 1.6% purity at 56.1 ± 1.7% recovery rate. Infrared spectroscopy and NMR spectroscopy analysis indicated that the structure of resulting PSA was identical to the published α-2,8 linked polysialic acid.