Phage infection is common during the production of L‐threonine by E. coli, and low L‐threonine production and glucose conversion percentage are bottlenecks for the efficient commercial production of L‐threonine. In this study, 20 antiphage mutants producing high concentration of L‐threonine were obtained by atmospheric and room temperature plasma (ARTP) mutagenesis, and an antiphage E. coli variant was characterized that exhibited the highest production of L‐threonine Escherichia coli ([E. coli] TRFC‐AP). The elimination of fhuA expression in E. coli TRFC‐AP was responsible for phage resistance. The biomass and cell growth of E. coli TRFC‐AP showed no significant differences from those of the parent strain (E. coli TRFC), and the production of L‐threonine (159.3 g L⁻¹) and glucose conversion percentage (51.4%) were increased by 10.9% and 9.1%, respectively, compared with those of E. coli TRFC. During threonine production (culture time of 20 h), E. coli TRFC‐AP exhibited higher activities of key enzymes for glucose utilization (hexokinase, glucose phosphate dehydrogenase, phosphofructokinase, phosphoenolpyruvate carboxylase, and PYK) and threonine synthesis (glutamate synthase, aspartokinase, homoserine dehydrogenase, homoserine kinase and threonine synthase) compared to those of E. coli TRFC. The analysis of metabolic flux distribution indicated that the flux of threonine with E. coli TRFC‐AP reached 69.8%, an increase of 16.0% compared with that of E. coli TRFC. Overall, higher L‐threonine production and glucose conversion percentage were obtained with E. coli TRFC‐AP due to increased activities of key enzymes and improved carbon flux for threonine synthesis.

中文翻译：

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通过大气和室温等离子体诱变获得的用于更高产量的 L-苏氨酸的抗噬菌体大肠杆菌突变体。

在大肠杆菌生产 L-苏氨酸过程中，噬菌体感染很常见，低 L-苏氨酸产量和葡萄糖转化率低是 L-苏氨酸高效商业化生产的瓶颈。在这项研究中，通过常压和室温等离子体 (ARTP) 诱变获得了 20 个产生高浓度 L-苏氨酸的抗噬菌体突变体，并表征了一个抗噬菌体大肠杆菌变体，其表现出最高的 L-苏氨酸大肠杆菌产量（[ E .大肠杆菌] TRFC-AP）。大肠杆菌TRFC-AP中fhu A 表达的消除是导致噬菌体抗性的原因。大肠杆菌的生物量和细胞生长TRFC-AP与亲本菌株（E.coli TRFC）无显着差异，L-苏氨酸产量（159.3 g L ^-1）和葡萄糖转化率（51.4%）分别提高了10.9%和9.1% ，分别与大肠杆菌TRFC 的那些进行比较。在苏氨酸生产期间（培养时间为 20 小时），大肠杆菌TRFC-AP 表现出更高的葡萄糖利用关键酶（己糖激酶、葡萄糖磷酸脱氢酶、磷酸果糖激酶、磷酸烯醇式丙酮酸羧化酶和 PYK）和苏氨酸合成（谷氨酸合酶、天冬氨酸激酶、高丝氨酸脱氢酶、高丝氨酸激酶和苏氨酸合酶）与大肠杆菌相比TRFC。代谢通量分布分析表明，苏氨酸与大肠杆菌TRFC-AP的通量达到69.8%，比大肠杆菌TRFC增加了16.0% 。总的来说，由于关键酶的活性增加和苏氨酸合成的碳通量增加，大肠杆菌TRFC-AP获得了更高的 L-苏氨酸产量和葡萄糖转化率。