Production Of N-Acetylglucosamine By Biosynthesis

N-acetylglucosamine(GlcNAc) is one of glucose derivatives, belonging to the functional amino sugar compounds. Widely used in the field of medicine, food and cosmetic ingredients. At present, the production of GlcNAc, mainly extracted from crab and shrimp shells by acid hydrolysis of chitin, which is not environmentally, and such production may be limited by geographical and seasonal restrictions. In addition, GlcNAc from shellfish may not be suitable for those people with shellfish allergies. Based on these disadvantages, recently developed methods to obtain GlcNAc in genetically modified microorganisms are favored by more and more scholars.This paper mainly focuses on the production of GlcNAc by microbial fermentation, the objectives of this work were:1. Optimization of producting GlcNAc by genetically modified E.coli at the flask shake level. Since this E.coli is metabolic engineered, firstly the induction conditions were optimized, and then the composition of the culture medium was optimized. The result indicated that when the OD60o up to 0.5-1 by adding 0.4mM IPTG, and an optimal medium comprising 40g/l initial glucose,6g/l NH4CI,5g/l yeastextract,12.8g/l Na2HPO4.7H2O,3g/l KH2PO4, 0.5g/l NaCl,5mM MgSO4.7H2O and 0.1mM CaCl2 could produce GlcNAc about 10.31g/1 in shake flask culture.2. Optimization of the production GlcNAc by scaling up in fermenter. Firstly, the effect of different rotational speed on the production of GlcNAc was studied by batch fermentation in 1L fermenter. Secondly, the effect of different concentration of glucose feeding on the production of GlcNAc was explored by fed-batch fermentation in 5L fermenter. Finally, the result shows that when the rotational speed was 600rpm, and feeding of concentration glucose 300g/l, the highest yield of GlcNAc was 31.69g/l, and the conversion rate of glucose was 27.37% in the 5L fermenter.3. The construction of C.glutamicum to produce GlcNAc. This is the first attempt to build a more secure strains C. glutamicum producing GlcNAc. Mainly through the amplification of two important enzymes of GlcNAc in the anabolic pathway. One of is glucosamine synthase gene glmS and another is glucosamine acetyltransferase gene gnal. And knocked out the catabolic pathway of N-acetylglucosamine and the by-product lactate synthesis pathway, eventually the C.glutamicum could produce GlcNAc 2.23g/l at shake flask level.