途径工程改造谷氨酸棒杆菌产莽草酸

Pathway Engineering Modification of Corynebacterium glutamicum for Shikimic Acid Production

莽草酸是一种芳香族中间代谢产物,也是合成抗禽流感药物磷酸奥司他韦的前体。目前,国内外莽草酸的生产主要依靠成本较高,周期较长的植物提取法。微生物发酵法合成莽草酸具有生产成本低、周期短等优势成为研究的热点。为了构建产莽草酸的重组谷氨酸棒杆菌,此次研究从基因组水平上对谷氨酸棒杆菌体内的莽草酸代谢途径进行代谢工程改造。通过阻断莽草酸分解代谢途径、解除反馈抑制以及阻断竞争性代谢途径的策略,实现了莽草酸产量的大幅提升。结果显示,所构建的重组谷氨酸棒杆菌SKA06经72 h摇瓶发酵,莽草酸产量达到7.61 g/L,相较出发菌种提升了68倍。并且,基于染色体工程的遗传改造策略克服了引入质粒带来传代不稳定、需要添加抗生素等问题,可以为莽草酸工程菌种的选育提供重要参考。

Shikimic acid,as an intermediate metabolite of aromatic family,is the precursor of oseltamivir phosphate for the synthesis of an anti-avian influenza drug.Currently,the production of shikimic acid mainly depends on the plant extraction method with shortcoming in high cost and long period.Due to the advantages in low production cost and short period,microbial fermentation for the synthesis of shikimic acid has turned into the hot spot of research.In order to construct a recombinant C.glutamicum capable of producing shikimic acid,the metabolic pathways of shikimic acid in C.glutamicum was modified via metabolic engineering at genetic level.The yield of shikimic acid significantly increased by blocking the catabolic pathway,relieving the feedback inhibition,and blocking the competitive metabolic pathway.The final strain C.glutamicum SKA06 produced 7.61 g/L of shikimic acid during 72 h shake flask cultivation,which was 68 times higher than that of the original strain.Moreover,genetic modification based on chromosome engineering overcame the problems of unstable passage and antibiotics addition caused by the introduction of plasmid,which may provide important reference for the development of shikimic acid producing strains.