The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, Jiangsu, People's Republic of China.
World J Microbiol Biotechnol. 2014 Feb;30(2):661-7. doi: 10.1007/s11274-013-1492-0. Epub 2013 Sep 26.
Dissolved oxygen is one of the most important bioprocess parameters that could affect cell growth and product formation, and it is easy to control by changing agitation speed. In this work, the effects of agitation speed on the performance of riboflavin production by recombinant Bacillus subtilis RF1 was investigated in fed-batch fermentation. The lower agitation speed (600 rpm) was beneficial for cell growth and riboflavin biosynthesis in the initial phase of fermentation process. While, during the later phase, higher agitation speed (900 rpm) was favor for cell growth and riboflavin biosynthesis. Thus, a two-stage agitation speed control strategy was proposed based on kinetic analysis, in which the agitation speed was controlled at 600 rpm in the first 26 h and then switched to 900 rpm to maintain high μ for cell growth and high q(p) for riboflavin production during the entire fermentation process. However, it was observed that a sharp increase of agitation speed resulted in an adverse effect on cell growth and riboflavin synthesis within a short time. To avoid this phenomenon, a multi-stage agitation speed control strategy was set up based on the two-stage control strategy, the maximum concentration of riboflavin reached 9.4 g l(-1) in 48 h with the yield of 0.051 g g(-1) by applying this strategy, which were 20.5 and 21.4% over the best results controlled by constant agitation speeds.
溶解氧是影响细胞生长和产物形成的最重要的生物过程参数之一，通过改变搅拌速度很容易控制。在这项工作中，在分批补料发酵中研究了搅拌速度对重组枯草芽孢杆菌 RF1生产核黄素性能的影响。较低的搅拌速度（600rpm）有利于发酵过程初始阶段的细胞生长和核黄素生物合成。而在后期，较高的搅拌速度（900rpm）有利于细胞生长和核黄素生物合成。因此，基于动力学分析提出了一种两阶段搅拌速度控制策略，其中在最初的 26 小时内将搅拌速度控制在 600rpm，然后切换到 900rpm，以在整个发酵过程中保持高μ用于细胞生长和高 q(p)用于核黄素生产。然而，观察到搅拌速度的急剧增加会在短时间内对细胞生长和核黄素合成产生不利影响。为了避免这种现象，基于两阶段控制策略设置了多阶段搅拌速度控制策略，通过应用该策略，在 48 小时内将核黄素的最高浓度达到 9.4gl(-1)，产率达到 0.051gg(-1)，比恒定搅拌速度控制的最佳结果提高了 20.5%和 21.4%。
