Abstract:Athrobacter luteu β-1,3-glucanase (βglⅠ) specifically acts on β-1,3-glycosidic bonds in β-glucan, which has outstanding advantages in yeast lytic activity. However, the expression level of βglⅠis low resulting in high cost of its production. This study achieved the secretory expression of βglⅠ by using seamless cloning technology in Bacillus subtilis, and improved the extracellular production of βglⅠ by optimizing expression elements such as Tat and Sec signal peptides, RBS and 5′UTR. The results showed that the signal peptide SPLipA increased the expression level of βglⅠ by 0.4 times. Then, RBS and 5′UTR were compared on the basis of this signal peptide, and the yield of βglⅠincreased by cry3A 5′UTR was 1.2 times higher than that of the parent strain. In addition, a Ni2+ affinity chromatography column was used to purify βglⅠ and its enzymatic properties were studied. The results showed that the optimum temperature and pH was 50 ℃ and pH 6.0, respectively. βglⅠwas more stable in the range of 0～45 ℃ and pH 4.0～9.0, and the specific activity of βglⅠ was 973 U/mg.
