3-Hydroxypropionic acid (3-HP) is an important platform synthesis block for sets of chemicals, but the relatively low production of 3-HP from biological sources presented major barriers for its industrial applications. In this study, a dual-substrate fermentative strategy by glycerol and glucose was proposed, and the aim was to evaluate the effect of different substrate addition strategies on the fermentation process. The results indicated that the optimal cosubstrate was glucose (20 g/L), and the enzymatic activity of aldehyde dehydrogenase (AldH) could be improved 3.5-fold as compared with no glucose addition. Continuous fed-batch fermentation at a constant speed displayed better 3-HP production of 17.20 g/L and highest specific 3-HP productivity of 1.79 mmol/(g cell·H) than the other fed-batch mode. The addition of glucose could greatly reduce the imbalance of the activity between glycerol dehydratase and AldH and provide a feasible method for improving 3-HP production. These results would be helpful in developing the 3-HP fermentation process.

3-Hydroxypropionic acid (3-HP) is an important compound and precursor for a series of chemicals and polymeric materials. In this study, the 3-HP producing bacteria were constructed and studied for efficient synthesis of 3-HP. The results indicated that the instability of glycerol dehydratase (GDHt) affected the 3-HP production significantly, which was successfully solved by the expression of glycerol dehydratase reactivase (GdrB), with fivefold increase in 3-HP yield. Meanwhile, NAD-regenerating enzymes GPD1 (glycerol-3-phosphate dehydrogenase) was expressed; however, the results showed 3-HP was significantly decreased from 56.73-4 mM, and malic acid was obviously increased. Analysis of the C flux distribution showed that the main reason for the results was the lack of NAD. The addition of NAD further increased the 3-HP production to 23.87 mM, demonstrating that the "regeneration of NAD" was the major factor for enhancing 3-HP production.

No abstract