ε-聚赖氨酸发酵过程的活性变化及发酵调控

Enhanced ε-poly-L-lysine production by improving cellular activity during fermentation

【目的】作为一种次级代谢产物,ε-聚赖氨酸生物合成受不同因素制约,为评价细胞活性对ε-聚赖氨酸生物合成的影响,研究发酵过程细胞活性、ε-聚赖氨酸合成及其它发酵参数变化,基于此改进发酵工艺。【方法】以Bac Light Live/Dead和5-氰基-2,3-二甲苯基氯化四唑(5-cyano-2,3-ditolyl tetrazolium chloride,CTC)为荧光探针,激光扫描共聚焦显微镜监测不同发酵时期细胞活性,并分析pH、细胞生长、ε-聚赖氨酸生物合成以及葡萄糖利用;通过向ε-聚赖氨酸合成期细胞添加酵母粉调控细胞活性改进发酵工艺。【结果】Bac Light Live/Dead为探针的共聚焦显示ε-聚赖氨酸发酵过程生长期(0-16 h)的细胞大都具有活性;CTC作为探针的分析显示生长期及ε-聚赖氨酸合成期前期(16-30 h)细胞活性高,ε-聚赖氨酸合成终止时细胞仅显示微弱活性;调控ε-聚赖氨酸合成期细胞活性的发酵工艺ε-聚赖氨酸终浓度达2.24 g/L(对照1.04 g/L)。【结论】调控ε-聚赖氨酸合成期细胞活性的发酵工艺可有效促进ε-聚赖氨酸生物合成。

[Objective] To assess the effect of cellular activity on ε-poly-l-lysine（ε-PL） biosynthesis and thereby to rationally improve the production,we studied the cellular activity,ε-PL formation and other parameters cross flask fermentation by Streptomyces ahygroscopicus.[Methods] Laser scanning confocal microscopy and a colorimetric method were used to determine cellular activity using Bac Light Live/Dead and 5-cyano-2,3-ditolyl tetrazolium chloride（CTC） as viable stains.To enhance the activity of the cells in the ε-PL production period,yeast extract was added.[Results]During ε-PL submerged fermentation in flasks,most cells were active in the growth period（0-16 h）; cells had metabolic activity in the growth and earlier ε-PL production periods between 0 and 30 h fermentation.Almost no activity was detected after 48 h fermentation when no ε-PL was produced.The improved fermentation achieved 2.24 g/L ε-PL from1.04 g/L.[Conclusion] Biosynthesis of ε-PL can be boosted by up-regulating cell activity in its production phase.