Abstract: Agitation is one of the main factors affecting fermentation process. To take advantage of advantages of individual impellers，impeller combination is necessary in improving agitation and fermentation efficiency. Four different impeller combinations (DT and DT，DT and BT6，CM6 and DT as well as CM6 and BT6) were simulated with the commercial fluid dynamics (CFD) software Fluent and their flow patterns and mixing times were compared. Mixing time was also validated by experiments. The optimal combination was the CM6 (upper impeller) and BT6 (lower impeller). Using this impeller combination，the maximal transglutaminase activity and biomass of Streptomyces hygroscopicus WSH03-13 reached 4.7U/mL and 42.9g/L respectively，which were 53% and 40.9% higher than the control group (DT and DT). The optimized impeller combination could promote microbial growth and fermentation process. The results in this study will be useful for further application of impeller combination in microbial fermentation.

Key words: impeller combination, numerical simulation, transglutaminase, fermentation, computational fluid dynamics

摘要： 搅拌是影响发酵过程的主要因素之一，组合不同类型搅拌桨、发挥其各自优势，势必能够优化搅拌性能、提高微生物发酵生产效率。本研究采用计算流体力学（CFD）方法，模拟六直叶涡轮桨（DT）和DT、DT和抛物线桨（BT6）、六斜叶桨（CM6）和DT以及CM6和BT6四种搅拌桨组合对流场和混合时间的影响。对模拟得到的混合时间进行实验验证。结果表明，最优组合为：上桨叶为CM6桨，下桨叶为BT6桨。吸水链霉菌WSH03-13产谷氨酰胺转胺酶（TG）的发酵实验结果表明：CM6和BT6桨组合可获得最高的谷氨酰胺转胺酶活性和生物量，分别为4.7U/mL和42.9g/L，较优化前（DT和DT桨）分别提高了53%和40.9%，说明优化后的搅拌桨组合更有利于微生物生长和发酵。研究结果为组合搅拌桨在微生物发酵过程中的应用提供了借鉴。

关键词: 桨叶组合, 数值模拟, 谷氨酰胺转胺酶, 发酵, 计算流体力学