To maximize the final lactic acid productivity and concentration, temperature control was optimized using a mathematical modelling approach. A kinetic model, including cell growth, product formation and substrate consumption equations, was proposed to describe the lactic acid production process by Escherichia coli AC-521 with glycerol as the substrate. By constructing four functions, the temperature effect was introduced on the fermentation process, where four parameters ( X _(max) , μ _(max) , Y _(ps) and β ) were observed to be significantly affected by the temperature. For the convenience of application, the temperature control strategies were simplified by dividing the whole fermentation process into several units. In each unit, the temperature was controlled constantly. Based on the model, the optimal temperature for each unit was determined to maximize the final lactate productivity. This temperature control strategy can be effectively applied in batch and fed-batch cultures, and the verified experimental evaluation showed a good correlation with the model data. Under improved temperature control conditions, a maximal lactic acid concentration of 90.4 g L ~(?1) was obtained after 80 h of fed-batch fermentation, giving a productivity of 1.13 g L ~(?1) h ~(?1) , which is 1.2 times more than that in the conventional constant temperature during the cultivation course.
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机译：为了使最终的乳酸生产率和浓度最大化，使用数学建模方法优化了温度控制。提出了包括细胞生长，产物形成和底物消耗方程在内的动力学模型，用以描述以甘油为底物的大肠杆菌AC-521的乳酸生产过程。通过构造四个函数，在发酵过程中引入了温度效应，其中四个参数（X _（max），μ_（max），Y _（ps）和β）受到温度的显着影响。为了方便应用，将整个发酵过程分为几个单元，简化了温度控制策略。在每个单元中，温度是恒定控制的。基于该模型，确定每个单元的最佳温度以最大程度地提高最终乳酸生产率。该温度控制策略可以有效地应用于分批和补料分批培养，经验证的实验评估表明与模型数据具有良好的相关性。在改进的温度控制条件下，分批补料发酵80小时后最大乳酸浓度为90.4 g L〜（？1），生产率为1.13 g L〜（？1）h〜（？1），是培养过程中常规恒温的1.2倍。
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