应用pH-shift控制策略制备丁酸新工艺及其优化

A Novel Preparation Technology for Butyric Acid Production by Using pH-shift Control Strategy and Its Optimization

以嗜热丁酸梭菌为生产菌株，研究不同pH（6．0，6．2，6．4，6．6，6．8，7．0）条件对嗜热丁酸梭菌生长和产酸的影响。基于不同pH条件下试验结果的分析比较，拟采用pH．shift控制策略，运用发酵法制备丁酸，并探索最优工艺条件。通过单因素试验和正交优化试验确定了最优发酵工艺条件为：0～20h将pH控制在6．8，而后将pH调低至6．2并保持到发酵结束，发酵温度为55℃，发酵总时间为50h，vR6mol／LNaOH溶液为中和剂，采用自动流加方式。优化后的发酵工艺能有效提高丁酸产量，通过应用pH．shif啦制策略，丁酸产量达16．12g／L，与固定pH条件下发酵最好结果相比提高35．69％。该试验结果表明采用pH．shi罐制策略的新工艺可有效提高丁酸发酵过程的效率。

Batch fermentations by Clostridium thermobutyricum ATCC49875 at various pH values ranging from 6.0 to 7.0 were investigated, and effects ofpH on cell growth and butyric acid production was researched. Based on the analysis of the experimental results, a two-stage pH-shift control strategy was proposed to use for butyric acid production, and the optimal process conditions were explored. The optimum fermentation conditions by single-factor experiment and orthogonal experi- ment were determined： At the first 20 h, pH was controlled at 6.8, and subsequently pH 6.2 was used, temperature was 55 ℃, 6 mol/L NaOH solution as neutralizing agent, the fermentation time was 50 h. Under the optimal conditions, the yield of butyric acid was 16.12 g/L by using pH-shift control strategy, which increased 35.69%, compared with the best results of constant pH process. These results showed the novel fermentation technology by using that pH-shift could get a significant improvement on the fermentation efficiency.