Environmental Microbial Technology Center of Hubei Province, Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, College of Life Sciences, Hubei University, 368 Youyi Avenue, Wuchang District, Wuhan, 430062, Hubei, People's Republic of China.
Lifecome Biochemistry Co. Ltd., Nanping, 353400, People's Republic of China.
Appl Biochem Biotechnol. 2019 Apr;187(4):1502-1514. doi: 10.1007/s12010-018-2894-0. Epub 2018 Sep 28.
Bacitracin, a kind of cyclic peptide antibiotic mainly produced by Bacillus, has wide ranges of applications. NADPH generation plays an important role in amino acid synthesis, which might influence precursor amino acid supply for bacitracin production. In this study, we want to improve bacitracin yield by enhancing intracellular precursor amino acids via strengthening NAPDH generation pathways in the bacitracin industrial production strain Bacillus licheniformis DW2. Based on our results, strengthening of NADPH pathway genes (zwf, gnd, ppnk, pntAB, and udhA) could all improve bacitracin yields in DW2, and the glucose-6-phosphate dehydrogenase Zwf overexpression strain DW2::Zwf displayed the best performance, the yield of which (886.43 U/mL) was increased by 12.43% compared to DW2 (788.40 U/mL). Then, the zwf transcriptional level and Zwf activity of DW2::Zwf were increased by 12.24-fold and 1.57-fold; NADPH and NADPH/NADH were enhanced by 61.24% and 90.63%, compared with those of DW2, respectively. Moreover, the concentrations of intracellular precursor amino acids (isoleucine, leucine, cysteine, ornithine, lysine, glutamic acid) were all enhanced obviously for bacitracin production in DW2::Zwf. Collectively, this research constructed a promising B. licheniformis strain for industrial production of bacitracin, more importantly, which revealed that strengthening of NADPH generation is an efficient strategy to improve precursor amino acid supplies for bacitracin production.
杆菌肽是一种主要由芽孢杆菌产生的环肽抗生素，应用广泛。NADPH 的生成在氨基酸合成中起着重要作用，可能会影响杆菌肽生产的前体氨基酸供应。在本研究中，我们希望通过增强 NADPH 生成途径来提高杆菌肽工业生产菌株地衣芽孢杆菌 DW2 中的细胞内前体氨基酸，从而提高杆菌肽的产量。基于我们的研究结果，增强 NADPH 途径基因（zwf、gnd、ppnk、pntAB 和 udhA）均可提高 DW2 中的杆菌肽产量，而葡萄糖-6-磷酸脱氢酶 Zwf 过表达菌株 DW2::Zwf 的表现最佳，其产量（886.43 U/mL）比 DW2（788.40 U/mL）提高了 12.43%。然后，DW2::Zwf 的 zwf 转录水平和 Zwf 活性分别提高了 12.24 倍和 1.57 倍；NADPH 和 NADPH/NADH 分别提高了 61.24%和 90.63%。此外，DW2::Zwf 中用于杆菌肽生产的细胞内前体氨基酸（异亮氨酸、亮氨酸、半胱氨酸、精氨酸、赖氨酸、谷氨酸）的浓度均明显提高。总的来说，本研究构建了一种有前途的地衣芽孢杆菌菌株，用于杆菌肽的工业生产，更重要的是，这揭示了增强 NADPH 的生成是提高杆菌肽生产前体氨基酸供应的有效策略。
