氧载体对小白链霉菌发酵生产ε-聚赖氨酸的影响

Effect of oxygen-vectors on the production of ε-poly-L-lysine

摘要:

为了有效改善发酵体系中的溶氧水平，提高小白链霉菌Streptomyces albulus PD-1发酵生产ε-聚赖氨酸的能力，文中通过对氧载体的种类、最佳添加浓度以及添加时间进行筛选，最终确定在0 h添加0.5% (V/V) 的正十二烷促进ε-聚赖氨酸生产效果最佳。在5 L发酵罐0 h添加0.5%的正十二烷进行批次补料发酵，ε-聚赖氨酸的产量和菌体干重分别可以达到 (30.8±0.46) g/L和 (33.8±0.29) g/L，较之对照组分别提高了31.6%和20.7%。ε-聚赖氨酸的产量和菌体干重的提高归因于0.5%正十二烷的添加促进发酵液中溶氧水平从23.8%提高到32%，同时发酵液中的一种主要副产物 (聚二氨基丙酸) 的含量下降31%。实验结果表明，正十二烷的添加可以提高S. albulus PD-1发酵液中的溶氧水平，抑制副产物的生成，促进ε-聚赖氨酸的合成。

Abstract:

To enhance the production of ε-poly-L-lysine (ε-PL) by improving dissolved oxygen level of the fermentation system, different oxygen-vectors were added to broth and n-dodecane was screened as the best oxygen-vector. The best amount of n-dodecane was 0.5% (V/V) and the best time was at start of the fermentation. In a fed-batch fermentation in a 5 L bioreactor, ε-PL concentration reached a maximum of (30.8±0.46) g/L and the dry cell weight obtained was (33.8±0.29) g/L, increasing by 31.6% and 20.7% compared with the control group, respectively. This improvement can be related to 0.5% n-dodecane could maintain dissolved oxygen concentration >32% of air concentration compared with 23.8% in ε-PL production phase, and the production of a main by-product, poly-L-diaminopropionic acid, fell by 31%. These results indicated that the dissolved oxygen level in the broth was improved by adding n-dodecane, which can inhibit the by-product production and improve the biosynthesis of ε-PL.