Tunable decoupled overproduction of lactobionic acid in Pseudomonas taetrolens through temperature-control strategies

Abstract

Triggering the switch from growth to lactobionic acid formation in Pseudomonas taetrolens is crucial to attain a high-yield bio-production system. This study elucidates how the growth-coupled and uncoupled lactobionic acid formation ratio can be modulated through the application of temperature-control strategies. Whereas the combination of high initial cell densities with a temperature value of 30 °C stimulated the onset of the lactobionic acid production phase from early cultivation times, temperature-stat conditions below 28 °C and above 30 °C led to a growth-coupled lactobionic acid formation with reduced cell growth. Further implementation of a temperature-control bioprocessing strategy at 28 °C with a pH-shift cultivation at 6.5 resulted in higher lactobionic acid yields (98%), volumetric productivity (2.04 g/L h), and specific productivity rates (1.73 g/g h) within only 24 h. Controlling the culture temperature at 28 °C via either temperature-stat or -shift bioprocessing strategies led to an overproduction of lactobionic acid, overcoming the low-yield mixed-growth-associated production patterns found at temperatures different than 28 °C. This novel temperature-driven approach provides a step forward in the bio-based production of lactobionic acid at high specific production rates and yields by uncoupling completely the production phase from the cell growth.