a School of Life Sciences of Shanxi Datong University , Datong Shanxi , China.
Bioengineered. 2019 Dec;10(1):52-58. doi: 10.1080/21655979.2019.1600966.
Trans-4-hydroxy-L-proline (Hyp) production by Escherichia coli (E. coli) in fermentation is a high-oxygen-demand process. E. coli secretes large amounts of soluble protein, especially in the anaphase of fermentation, which is an important factor leading to inadequate oxygen supply. And acetic acid that is the major by-product of Hyp production accumulates under low dissolved oxygen (DO). To increase DO and achieve high-level Hyp production, soluble protein was hydrolysed by adding protease in Hyp fermentation. The optimal protease, concentration, and addition time were trypsin, 0.2 g/L, and 18 h, respectively. With the addition of trypsin, the soluble protein in Hyp fermentation decreased by 43.5%. The DO could be maintained at 20-30% throughout fermentation. Hyp production and glucose conversion rate were 45.3 g/L and 18.1%, which were increases of 24.1% and 8.4%, respectively. The accumulation of acetic acid was decreased by 52.1%. The metabolic flux of Hyp was increased by 44.2% and the flux of acetate was decreased by 51.0%.
大肠杆菌（E. coli）发酵生产反-4-羟脯氨酸（Hyp）是一个需氧量高的过程。E. coli 会大量分泌可溶性蛋白，尤其是在发酵后期，这是导致供氧不足的重要因素。而 Hyp 生产的主要副产物乙酸在低溶解氧（DO）下积累。为了增加 DO 并实现高水平的 Hyp 生产，在 Hyp 发酵中添加蛋白酶水解可溶性蛋白。最佳的蛋白酶、浓度和添加时间分别为胰蛋白酶、0.2 g/L 和 18 h。添加胰蛋白酶后，Hyp 发酵中的可溶性蛋白降低了 43.5%。整个发酵过程中 DO 可维持在 20-30%。Hyp 产量和葡萄糖转化率分别为 45.3 g/L 和 18.1%，分别提高了 24.1%和 8.4%。乙酸的积累减少了 52.1%。Hyp 的代谢通量增加了 44.2%，乙酸的通量减少了 51.0%。
