Production Of Glcnac By Biosynthesis

N-acetylglucosamine(GlcNAc)is a crucial amino sugar and plays an important role in various organisms,such as human body and microorganisms.It is widely used in the food,pharmaceutical and cosmetic industries.As so far,GlcNAc is mainly produced by chemical methods.However,the main raw materials for chemical methods is the exoskeletons of crustaceans,such as shrimps and crabs.These raw materials have problems,for example,origin and season restrictions,and chemical processes produce more serious problems in the production of GlcNAc.Due to these constraints,biosynthesis of GlcNAc has become a new option.The raw materials for biosynthesis of GlcNAc are generally based on biomass.The production process has less environmental pollution compared to chemical methods.In this article,Corynebacterium glutamicum was chosen as the object for metabolic pathway synthesis and synthesis of GlcNAc.The main purpose of this paper is to improve the production of GlcNAc by optimizing the synthesis pathway in Corynebacterium glutamicum ATCC13032.The main work of this paper is as follows:(1)Gene glnA was overexpressed to enhance the expression of glutamine synthesis pathway in the C.glutamicum,which increased the titer of glutamine.The GlcNAc yield of recombinant C.gW-SG reached 2.34 g/L.Gene poxB was knocked out to block the by-product acetate synthesis pathway and gene GNA1 was integrate into the chromosome of C.glutamicum,which was control the key enzyme in the GlcNAc pathway.The GlcNAc yield of recombinant C.gWBG-SGA reached 2.62 g/L.(2)The glycolysis,which was the main competitive pathway of the GlcNAc pathway,was weakened by weakening the key gene pfkA.Anti-sense RNA and CRISPi were used to weaken the gene.The best weaken effect was that the strain C.gWBG-SGAA1 weakened by anti-sense RNA,GlcNAc yield of which reached 3.11 g/L.(3)It was determined that the optimum addition time and concentration of inducer during the fermentation of strain C.gWBG-SGAA1 were 2 h after inoculation and 0.8 mM IPTG.The concentration of important components in the fermentation medium was optimized.When the glucose concentration was 85 g/L,the corn slurry concentration was 40 g/L,and the urea concentration was 5 g/L,the GlcNAc yield produced by strain C.gWBG-SGAA1 reached 4.48 g/L.