联动过程控制技术提高10 L发酵罐γ-聚谷氨酸产量

Improvement of γ-Polyglutamic Acid Production in 10 L Fermenter by Linkage Process Control Technology

聚谷氨酸,是由微生物发酵产生的水溶性多聚氨基酸,分子量多分布在100~10000 kD,因其具有水溶性和吸附性好,以及易降解等特点,多用于农业、环保、医药等领域。本研究以实验室自行筛选的一株产γ-聚谷氨酸的地衣芽孢杆菌为出发菌株,在10 L发酵罐上对接种量、转速、风量、pH、发酵时间等发酵条件进行优化研究,旨在提高γ-聚谷氨酸产量。实验结果表明,当设定初始发酵条件为接种量10%,初始转速220 r/min,通风量8 L/min,pH值7.4,发酵过程中对转速、发酵液pH、风量进行联动控制调整,在发酵20 h后上调转速到250 r/min,DO低于20%风量提高到10 L/min,发酵液pH值由7.4降低至6.0左右时,对流加浓度为20%的氨水进行pH调整控制,维持pH值在7.0,65 h后发酵结束,可明显提高γ-聚谷氨酸产量,由未优化控制条件前的8.9 g/L提高到21.6 g/L。因此,通过对转速、pH、通风量的协同联动调整,γ-聚谷氨酸的产量有了较大幅度提升,将为后期的扩大化生产奠定基础。

polyglutamic acid is the water-soluble polyamino acid that produced by microbial fermentation.Its molecular weight is mostly distributed in 100~10000 kD.Because of the features of water solubility,good adsorption and easy degradation,it is widely used in agriculture,environmental protection,medicine and other fields.This experiment is based on a Bacillus licheniformis,selected by our laboratory staff,which can produceγ-polyglutamic acid.The fermentation conditions such as inoculum size,rotation speed,aeration rate,pH and fermentation time were optimized on a 10 L fermenter to increase the yield ofγ-polyglutamic acid.Initial fermentation conditions:Inoculum size 10%,rotation speed 220 r/min,aeration rate,pH 7.4.Through the linkage control of the rotation speed,fermentation liquid pH and air volume in the fermentation process,the specific method is:After 20 h fermentation,the rotation speed is increased to 250 r/min,DO is less than 20%,the air volume is increased to 10 L/min,and the fermentation liquid pH reduced from 7.4 to 6.0.Fed-batch 20%ammonia water for p H adjustment control,maintaining pH at 7.0.After 65 h of fermentation,the yield ofγ-polyglutamic acid was significantly increased,which was increased from 8.9 g/L to 21.6 g/L before the optimal control conditions.Therefore,through the coordinated adjustment of rotation rate,pH and aeration rate,the production ofγ-polyglutamic acid has been greatly increased,which will lay a foundation for the later expansion of production.