基因敲除弱化产1,3-丙二醇Klebsiella pneumoniae荚膜多糖的合成

Reducing the capsular polysaccharide synthesis of Klebsiella pneumoniae in 1,3-propanediol fermentation by genes knocking-out

1,3-丙二醇(1,3-PDO)是重要的平台化合物,在高性能纤维合成等领域具有广泛应用。Klebsiella pneumoniae是优良的1,3-PDO生物合成细胞工厂,但该菌代谢甘油合成1,3-PDO时积累大量荚膜多糖,影响底物与产物的高效转运,导致发酵液黏度增大,限制发酵法生产1,3-丙二醇的下游提取及产业化。本研究基于已报道的K.pneumoniae荚膜合成途径,利用Red重组技术对K.pneumoniae荚膜多糖合成途径中的起始糖基转移酶wec A基因及参与荚膜多糖后期组装的跨膜蛋白wzi基因进行敲除,并考察上述基因缺失对菌株荚膜含量、细胞形态、菌体生长、发酵液黏度及产物合成的影响。研究发现,同时缺失wec A和wzi基因对于弱化荚膜多糖效果显著,荚膜含量降低38.5%,细胞基本丧失菌毛合成及相互粘连能力,1,3-PDO产量提高23.0%,为菌株改造提供了一种新思路。

1,3-propanediol(1,3-PDO)is an important platform compound and has been widely used in the production of high performance fiber synthesis.Klebsiella pneumoniae is an excellent1,3-PDO biosynthetic cell factory.However,the capsular polysaccharide accumulation of K.pneumonia increased the viscosity of fermentation broth and impacted the efficient transport of substrate and product,resulting in an obstacle in downstream extraction and industrialization of1,3-PDO.In this study,by analyzing the capsular synthesis pathway of K.pneumoniae,the key genes wecA(initial glycosyltransferase gene)and wzi involved in the assembly of capsular polysaccharide were disrupted by Red recombinant system.The effects of genes deletion on capsule content,cell morphology,cell growth,broth fluid viscosity,and product synthesis,were studied.The capsular content was reduced by38.5%,which led to the loss of cells fimbriae synthesis ability and the adhesion,and the titer of1,3-PDO increased by23.0%.The study provided a novel prospect on the development of K.pneumoniae on the production of1,3-PDO.