Process engineering towards an oxidative cellular state improves 3-hydroxypropionic acid production with Lentilactobacillus diolivorans.

ABSTRACT

3-hydroxypropionic acid (3-HP) is among the top platform chemicals proposed for bio based production by microbial fermentation from renewable resources. A promising renewable substrate for 3-HP production is crude glycerol. Only a few microorganisms can efficiently convert glycerol to 3-HP. Among the most promising organisms is Lentilactobacillus diolivorans. In this study, an already established fed-batch process, accumulating 28 g/L 3-HP, was used as a starting point for process engineering. The engineering approaches focused on modulating the cellular redox household towards a more oxidized state, as these conditions favour 3-HP production. Variations of oxygen and glucose availability (controlled by the glucose/glycerol ratio in the feed medium) individually already improved 3-HP production. However, the combination of both optimal parameters (30% O2, 0.025 mol/mol glu/gly) led to the production of 67.7 g/L 3-HP after 180 h of cultivation, which is so far the highest titer reported for 3-HP production using Lactobacillus spp.