Abstract:

The DNA contents, the internal grain densities, the surface roughness and the cell sizes of Serratia marcescens ZSG cells were detected to have different changes by the flow cytometry when ZSG cells were cultivated in the medium with the different carbon sources.Through mutagenizing compoundly ZSG cells, a stable mutant strain ZSG7 was gained, of which the prodigiosin(PG) production in the 250 ml conical flask and in 5 L fermentor were increased by 62.5% and 269% compared with the the original strain yields, respectively.PG production of fermentation with the optimal culture medium in the 250 ml conical flask was increased by 100% compared with the unoptimized.After dissolved oxygen(DO) was optimized by step controlling, the PG production was increased by 30.9% compared with the DO-unoptimized.After constant pH was optimized, the PG production was increased by 35.9% compared with the pH-unoptimized.After the fed-batch components were optimized, the PG production was increased by 47.6% compared with the batch fermentation with constant pH7.The kinetic models about bacteria growth and PG formation of the batch fermentation with constant pH7 and the fed-batch fermentation were built based on the Logistic equation and Luedeking-Piret equation.With the fitting model parameters, the models could provide reasonable description for the processes of the batch fermentation with constant pH7 and the fed-batch fermentation.

Key words: flow cytometry, carbon source, prodigiosin, kinetic modeling, mutagenesis, optimization, fermentation

摘要：

使用流式细胞仪研究了不同碳源对粘质沙雷氏菌ZSG新陈代谢的影响，发现不同碳源导致ZSG的DNA含量、细胞内部颗粒密度、表面粗糙度和细胞大小在发酵过程中呈现有差异的变化。对ZSG进行复合诱变筛得一株稳定突变菌株ZSG7，在250 ml摇瓶和5 L发酵罐中进行发酵，其灵菌红素（PG）产量比出发菌株分别提高了62.5%和269%。对ZSG7进行发酵培养基优化后PG产量比优化前提高了100%。对ZSG7发酵进行溶氧分段控制模式调控后PG产量比DO调控前提高了30.9%。对ZSG7发酵进行恒定pH调控后比pH调控前提高了35.9%。对ZSG7发酵进行补料组分优化后比补料前提高了47.6%。基于Logistic方程和Luedeking-Piret方程建立了恒定pH7分批发酵和补料分批发酵的菌体生长模型和PG合成模型。拟合模型参数后，模型可以合理地描述恒定pH7分批发酵和补料分批发酵的过程。

关键词: 流式细胞仪, 碳源, 灵菌红素, 动力学模型, 诱变, 优化, 发酵