高产碱性果胶酶吉氏芽孢杆菌的诱变育种与固态培养条件优化

Breeding of Bacillus gibsonii for alkaline pectinase production and its solid-state cultivation conditions

以吉氏芽孢杆菌(Bacillus gibsonii)S-2为出发菌株,经紫外线诱变育种,得到产碱性果胶酶较高的新菌株2249。优化后的固态培养基为甜菜粕5g、酵母膏0.15g、KH2PO40.0075g、Na2CO30.12g、水15mL、液体种子种龄为24h、接种量为2mL、培养温度为35℃、培养时间为72h,酶产率达到6.05kU/g(干甜菜渣),较出发菌株S-2提高68%。该酶的最适pH10.0、最适温度为55℃,NaCl、MgSO4、CaCl2、KCl对酶活有明显激活作用,CuSO4、ZnSO4对酶活有明显抑制作用。

A higher yield strain Bacillus gibsonii 2249 was obtained by UV mutagenesis from B. gibsonii S-2 for the production of alkaline pectinase. After inoculated with 2 mL of a 24-h-old inoculum culture and incubated at 35 ℃ for 72 h by solid-state cultivation, the maximum alkaline pectinase yield of 6.05 kU/g dry sugar beet pulp from Bacillus gibsonii 2249 was obtained in the medium which contained 5.0 g dry sugar beet pulp, 0.15 g yeast extract, 0.0075 g KH2PO4, 0.12 g Na2CO3 and 15 mL water, which was increased by 68% in contrast with that of its initial strain S-2. The highest activity of the crude enzyme from B. gibsonii 2249 was at pH 10 and 55℃. The activity of the enzyme was enhanced by NaCl, MgSO4, CaCl2, KCl, whereas was inhibited by CuSO4, ZnSO4.