解淀粉芽孢杆菌合成surfactin的发酵策略优化

Fermentation Optimization for the Production of Surfactin by Bacillus amyloliquefaciens

Surfactin作为一种绿色生物表面活性素在多种领域均有潜在的应用价值,但是在生产过程中存在着泡沫难以控制的问题,阻碍了其实现工业化生产。因此在7L发酵罐水平探究了适合surfactin工业化生产的最佳发酵策略。研究结果表明,过量添加消泡剂会对微生物的生长造成不利影响而且会增加生产成本,以有机硅和大豆油为消泡剂时surfactin产量分别为1.42g/L和1.96g/L。通过改进发酵罐采用泡沫分离的发酵策略,不仅可以经济有效地解决泡沫难以控制的问题,而且可以实现surfactin的原位分离,surfactin产量为2.39g/L;基于泡沫分离式发酵,控制pH=7后surfactin产量提高至3.45g/L;又进一步通过控制DO≥20%后产量提高至5.07g/L。最后,将泡沫分离耦合pH、溶解氧控制及恒速补料,控制pH=7、DO≥20%、恒速流加速度1.39ml/min,可以将surfactin产量显著提高至6.04g/L,与添加消泡剂相比,产量提高了4.25倍。以上结果为surfactin的工业化生产提供了依据。

Surfactin,as a green biosurfactant,can be widely applied in various fields.However,the severe foaming arising in the fermentation process obstructed the industrial production of surfactin.Therefore,different strategies were explored to solve this problem in a 7 L bioreactor.The results showed that excessive addition of antifoam would inhibit microbial growth and increase the production costs.The surfactin yield were 1.42 g/L and 1.96 g/L by using organic silicon and soybean oil as antifoams,respectively.However,foam fractionation in a modified bioreactor was more economical and effective for controlling the foaming and separating surfactin in situ.After fermentation coupled with foam fractionation,the surfactin yield was 2.39 g/L.Based on the strategy of foam fractionation,the surfactin yield increased to 3.45 g/L after controlling pH at 7.Moreover,it increased to 5.07 g/L after controlling pH at 7 and DO≥20%.Furthermore,the surfactin yield increased to 6.04 g/L by coupling foam fractionation with the regulation of pH,DO,and feeding(a constant rate of 1.39 ml/min),which was 4.25 times higher than using antifoam.An efficient strategy is provided to control the foaming during fermentation and increase the surfactin yield,which can promote the industrial production of surfactin.