高产PSA的基因工程菌株构建

Construction of Genetically Engineered Strains for High-Yield Polysialic Acid (PSA) Production

聚唾液酸(PSA)是一种具有重要生物功能的高分子多糖,广泛存在于自然界和人体中。由于其低免疫原性和良好的生物降解性,PSA被认为是一种理想的药物控释材料。本研究以大肠杆菌K87为出发菌株,通过过表达Neu5AC合成路径中的关键基因neuD,构建了高效合成PSA的基因工程菌株。通过摇瓶发酵和发酵罐发酵实验,验证了不同拷贝数neuD基因对PSA产量的影响。结果表明,高拷贝数表达载体能显著提高PSA的产量,其中E. coli K87-6菌株在5 L发酵罐中PSA产量达8.4 g/L,比出发菌株提高27%。本研究构建的高效合成PSA的基因工程菌株在工业生产中具有广泛的应用前景。Polysialic acid (PSA) is a high-molecular-weight polysaccharide with significant biological functions, widely found in nature and the human body. Due to its low immunogenicity and good biodegradability, PSA is considered an ideal material for drug delivery systems. In this study, Escherichia coli K87 was used as the starting strain to construct genetically engineered strains for efficient PSA production by overexpressing the key gene neuD in the Neu5AC synthesis pathway. The effects of different copy numbers of the neuD gene on PSA yield were verified through shake flask and fermenter experiments. The results showed that high-copy-number expression vectors significantly increased PSA yield, with the E. coli K87-6 strain achieving a PSA yield of 8.4 g/L in a 5 L fermenter, which is 27% higher than the starting strain. The genetically engineered strains constructed in this study have broad application prospects in industrial production.