Enhancement of Polysialic Acid Yield by Reducing Initial Phosphate and Feeding Ammonia Water to Escherichia coli CCTCC M208088
2010
Wu, Jian-Rong, Jiangnan University, Wuxi, China | Liu, Jin-Long, Jiangnan University, Wuxi, China | Zhan, Xiao-Bei, Jiangnan University, Wuxi, China | Lin, Chi-Chung, Jiangnan University, Wuxi, China | Zhao, Hui, Jiangnan University, Wuxi, China
Polysialic acid (PSA) is a capsular polysaccharide obtained from aerobic fermentation with Escherichia coli. To enhance PSA production and eliminate the influence of phosphate on the PSA purification process, a lower level of initial phosphate was adopted with pH control. The resulting PSA yield reached 4.1 g/L in fed-batch fermentation with 2.5 g/L K₂HPO₄ and E. coli strain CCTCC M208088. In addition, an ammonia water (NH₄OH) feeding strategy to control the pH at 6.4 was developed resulting in PSA production that reached as high as 5.2 g/L. NMR spectra confirmed the purified biopolymer as a α-2,8 linked PSA, identical to the published NMR spectra, with a molecular weight in the range of 16~50 kDa.
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