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

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.