the invention provides an effective method for improving n - acetylglucosamine production by engineered b . subtilis deletion of phosphoenolpyruvate carboxykinase encoding gene pcka and encoding pyruvate kinase gene pyk in recombinant glcnac - producing strain bsgnk - pxyla - glms - p43 - gna1 is first performed to enhance glcnac production , followed by overexpression of pyruvate carboxylase encoding gene pyca for facilitating cell growth . finally , the glcnac production of the recombinant strain bpts3 reached to 11 . 3 g / l , which was 1 . 84 - fold of bsgnk . this method can be used for improve cellular property of engineered b . subtilis for glcnac production , which can be further applied to industrial production of glcnac .