State Key Laboratory of Bioreactor Engineering, New World Institute of Biotechnology, East China University of Science and Technology, Shanghai 200237, People's Republic of China.
State Key Laboratory of Bioreactor Engineering, New World Institute of Biotechnology, East China University of Science and Technology, Shanghai 200237, People's Republic of China.
Bioresour Technol. 2018 Oct;265:328-333. doi: 10.1016/j.biortech.2018.06.001. Epub 2018 Jun 2.
Gluconobacter oxydans can be efficiently used to produce 3-hydroxypropionic acid (3-HP) from 1,3-propanediol (1,3-PDO). However, the enzymes involved remain unclear. In this study, transcription analysis of two mutants of strain DSM 2003, obtained by UV-mutagenesis, revealed that membrane-bound alcohol dehydrogenase (mADH) and membrane-bound aldehyde dehydrogenase (mALDH) might be the main enzymes involved. Through deletion and complementation of the genes adhA and aldh, mADH and mALDH were verified as the main enzymes responsible for 3-HP production. Then mALDH was verified as the rate-limiting enzyme in 3-HP production. Since that overexpression of mADH had no effect on 3-HP production, whereas overexpression of mALDH increased 23.6% 3-HP production. Finally, the 3-HP titer of 45.8 g/L and the highest productivity 1.86 g/L/h were achieved when the two mutants DSM 2003/adhAB and DSM 2003/aldh were mixed at a ratio of 1:2 (cell density) and used as whole cell catalysts for 3-HP production.
氧化葡萄糖酸杆菌可以有效地将 1,3-丙二醇（1,3-PDO）转化为 3-羟基丙酸（3-HP）。然而，其中涉及的酶仍不清楚。在这项研究中，通过紫外线诱变获得的 DSM 2003 两个突变株的转录分析表明，膜结合型醇脱氢酶（mADH）和膜结合型醛脱氢酶（mALDH）可能是主要相关酶。通过 adhA 和 aldh 基因的缺失和互补，证实 mADH 和 mALDH 是主要负责 3-HP 生产的酶。然后证实 mALDH 是 3-HP 生产中的限速酶。由于过表达 mADH 对 3-HP 生产没有影响，而过表达 mALDH 可使 3-HP 产量提高 23.6%。最后，当两个突变株 DSM 2003/adhAB 和 DSM 2003/aldh 以 1:2（细胞密度）的比例混合并用作 3-HP 生产的全细胞催化剂时，可获得 45.8 g/L 的 3-HP 浓度和 1.86 g/L/h 的最高生产速率。
