【摘要】 本文考察了六种搅拌桨组合对土壤杆菌产可得然胶发酵体系的体积溶氧系数(KLa)和溶氧(DO)水平的影响。搅拌桨组合5#(半圆管圆盘桨+半圆管圆盘桨+六直叶圆盘桨)能使发酵体系溶解氧始终保持在30%以上,其它搅拌桨组合不能满足发酵体系溶解氧要求。使用搅拌桨组合5#和组合6#时可得然胶产量、得率及生产强度好于其它搅拌桨组合,72 h可得然胶产量分别达到58. 2 g/L和56. 7 g/L,得率为0. 55 g/g蔗糖和0. 53 g/g蔗糖,生产强度达0. 81 g/L/h和0. 79g/L/h。使用搅拌桨组合5#时,发酵液粘度显著低于其它搅拌桨组合时发酵液粘度。随发酵时间延长,可得然胶分子量逐渐降低,而用搅拌桨组合5#时,分子量降低缓慢,发酵72 h时可得然胶分子量为1. 50×106Da。更多还原

【Abstract】 In this paper,the effects of six impeller paddle combinations on the volume O2 mass transfer coefficient( KLa)and dissolved oxygen( DO) in curdlan fermentation system by Agrobacterium sp. were investigated. The dissolved oxygen was above 30% in the fermentation process by using the impeller combination 5 #( semi-circular disc turbine + semicircular disc turbine + six straight blade disc turbine),while the dissolved oxygen of fermentation system was not enough by using other impeller combinations. The curdlan production,yield and productivity using impeller combination 5# and6# were higher than those using other impeller combinations. After 72 h,the curdlan production was 58. 2 g/L and 56. 7 g/L,curdlan yield was 0. 55 g/g and 0. 53 g/g of consumed sucrose,and the productivity was 0. 81 g/L/h and 0. 79 g/L/h respectively using impeller combination 5# and 6#. When the impeller combination 5# was used,the viscosity of the fermentation broth was significantly lower than those using other impeller combinations. With the prolonged fermentation time,the molecular weight of curdlan gradually decreased. The molecular weight of curdlan decreased slowly using the impeller combination 5# and the molecular weight was 1. 50 × 106 Da after 72 h fermentation.更多还原