氧化葡萄糖酸杆菌生物催化1,3-丙二醇合成3-羟基丙酸

Biosynthesis of 3-hydroxypropionic acid from 1,3-propanediol by Gluconobacter oxydans ZJB09112

摘要:

3-羟基丙酸是一种潜在的重要化工产品，可作为中间体合成多种有经济价值的工业用化合物。文中利用氧化葡萄糖酸杆菌生物催化1,3-丙二醇合成3-羟基丙酸。首先在50 mL摇瓶中 (转化体系为10 mL) 考察细胞加入量、底物和产物浓度等对催化反应的影响。在此基础上，在2 L鼓泡塔中 (转化体系为1 L)，采取适当的补料方式和生物转化与分离相耦合的手段解除抑制，以提高目标产物终浓度。结果表明：高底物和产物浓度通过降低反应初速度抑制转化的进行，并确定了最佳催化反应条件为6 g/L菌体量，pH 5.5。利用流加补料方式维持反应体系中底物浓度在15~20 g/L，经过60 h的反应，3-羟基丙酸的浓度达到60.8 g/L，生产强度为1.0 g/(L·h)，转化率为84.3％。采用生物转化与分离相耦合的方法，经过50 h的转化反应，3-羟基丙酸的总产量达76.3 g/L，生产强度为1.5 g/(L·h)，转化率83.7％。研究结果对利用氧化葡萄糖酸杆菌的不完全氧化醇类化合物特性实现其在工业生物催化中的应用具有一定的指导意义。

Abstract:

3-Hydroxypropionic acid is an important building block to synthesize lots of industrially valuable chemicals. In this study, we firstly investigated the effects of cell, substrate and product concentrations on biosynthesis of 3-hydroxypropionic acid from 1,3-propanediol by Gluconobacter oxydans ZJB09112 in 50-mL shake flask containing 10 mL transformation liquid. To avoid the inhibition of substrate and product, we adopted fed-batch biotransformation and fed-batch biotransformation coupled with in situ product removal in 2-L bubble column reactor containing 1 L transformation liquid. The results show that high concentrations of substrate and product could inhibit the biotransformation by decreasing the initial reaction rate, and the optimal reaction conditions were as follows: cell concentration 6 g/L, pH 5.5. Fed-batch biotransformation in which the substrate concentration was maintained at 15–20 g/L could obtain product concentration of 60.8 g/L after 60 h, which gave a productivity of 1.0 g/(L·h) and a yield of 84.3%. Furthermore, fed-batch biotransformation coupled with in situ product removal could achieve the total product concentration of 76.3 g/L after 50 h, which gave a productivity of 1.5 g/(L·h) and a yield of 83.7%. The results obtained here may be useful for the application of G. oxydans in biocatalysis industry by using its characteristic of incomplete oxidation of alcohols.