School of Biological Engineering, Dalian Polytechnic University, Dalian 116034, P.R. China.
Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P.R. China.
J Microbiol Biotechnol. 2019 Jun 28;29(6):923-932. doi: 10.4014/jmb.1901.01058.
Current strategies of strain improvement processes are mainly focused on enhancing the synthetic pathways of the products. However, excessive metabolic flux often creates metabolic imbalances, which lead to growth retardation and ultimately limit the yield of the product. To solve this problem, we applied a dynamic regulation strategy to produce L-phenylalanine (LPhe) in . First, we constructed a series of Phe-induced promoters that exhibited different strengths through modification of the promoter region of . Then, two engineered promoters were separately introduced into a Phe-producing strain xllp1 to dynamically control the expression level of one pathway enzyme AroK. Batch fermentation results of the strain xllp3 showed that the titer of Phe reached 61.3 g/l at 48 h, representing a titer of 1.36- fold of the strain xllp1 (45.0 g/l). Moreover, the L-Phe yields on glucose of xllp3 (0.22 g/g) were also greatly improved, with an increase of 1.22-fold in comparison with the xllp1 (0.18 g/ g). In summary, we successfully improved the titer of Phe by using dynamic regulation of one key enzyme and this strategy can be applied for improving the performance of strains producing other aromatic amino acids and derived compounds.
目前的菌株改良策略主要集中在增强产物的合成途径上。然而，过多的代谢通量往往会导致代谢失衡，从而导致生长迟缓，最终限制产物的产量。为了解决这个问题，我们在 中应用了一种动态调控策略来生产 L-苯丙氨酸 (LPhe)。首先，我们通过修饰 的启动子区域构建了一系列具有不同强度的苯丙氨酸诱导启动子。然后，两个工程启动子分别被引入到一个苯丙氨酸生产菌株 xllp1 中，以动态控制一条途径酶 AroK 的表达水平。菌株 xllp3 的分批发酵结果表明，在 48 h 时，phe 的产量达到 61.3 g/l，比菌株 xllp1（45.0 g/l）提高了 1.36 倍。此外，xllp3 的葡萄糖上 L-Phe 产量（0.22 g/g）也得到了极大提高，与 xllp1（0.18 g/g）相比增加了 1.22 倍。总之，我们成功地通过动态调控一个关键酶来提高了 Phe 的产量，并且该策略可以应用于提高生产其他芳香族氨基酸和衍生化合物的菌株的性能。
