链霉菌Streptomyces sp. M-Z18转化前体L-赖氨酸合成ε-聚赖氨酸的研究

ε-Poly-L-lysine Production from Precursor L-lysine by Streptomyces sp. M-Z18

目的:考察不同细胞培养方式对Streptomyces sp.M-Z18转化前体L-赖氨酸合成ε-聚赖氨酸过程的影响。方法:利用两阶段细胞培养和发酵过程流加方式,建立了两阶段细胞培养转化前体L-赖氨酸合成ε-聚赖氨酸以及转化前体L-赖氨酸耦合甘油发酵生产ε-聚赖氨酸的策略。结果:(1)两阶段细胞培养转化前体L-赖氨酸合成ε-聚赖氨酸策略实现ε-PL积累15 g/L,转化L-赖氨酸3 g/L;(2)转化前体L-赖氨酸耦合甘油发酵生产ε-聚赖氨酸策略使得ε-PL产量达到33.76 g/L,单位菌体的合成能力提高37.8%,转化L-赖氨酸4 g/L。这表明,上述两种方式下前体L-赖氨酸都能够被Streptomyces sp.M-Z18转化合成ε-聚赖氨酸,但转化效率还有待进一步提高。意义:揭示了Streptomyces sp.M-Z18合成ε-聚赖氨酸的限速步骤在于初级代谢产物L-赖氨酸的合成,这为后续利用代谢工程手段改造菌株提供了方向。

To investigate the process of ε-poly-L-lysine（ε-PL） production from precursor L-lysine under different culture conditions of Streptomyces sp.M-Z18,it has developed conversion of precursor L-lysine for ε-PL production,combined with two-stage culture method,and with fermentation from glycerol,respectively.The results of experiment showed that two-stage culture method was used for conversion L-lysine to ε-PL and attained at 15 g/L with biotransformation of 3 g/L L-lysine;Furthermore,ε-PL production from glycerol fermentation coupled with L-lysine conversion achieved 33.76 g/L ε-PL and enhanced ε-PL productivity at 37.8%,compared with L-lysine-free fermentation.It was demonstrated that ε-PL production could be derived from precursor L-lysine,however,the efficiency of this conversion is needed further improved.It has indicated that the limit of ε-PL production is the biosynthesis of L-lysine in primary metabolism.Meanwhile,the results presented here provide a guidance for the ε-PL-producing strains primary metabolism improvement by metabolic engineering,and an efficient approach to enhancement of ε-PL production in scale fermentation.