High-titer production of monomeric hydroxyvalerates from levulinic acid in Pseudomonas putida

Hydroxyacids represent an important class of compounds that see application in the production of polyesters, biodegradable plastics and antibiotics, and that serve as useful chiral synthetic building blocks for other fine chemicals and pharmaceuticals. An economical, high-titer method for the production of 4-hydroxyvalerate (4HV) and 3-hydroxyvalerate (3HV) from the inexpensive and renewable carbon source levulinic acid was developed. These hydroxyvalerates were produced by periodically feeding levulinate to Pseudomonas putida KT2440 expressing a recombinant thioesterase II (tesB) gene from Escherichia coli K12. The titer of 4HV in shake flask culture reached 13.9 ± 1.2 g L−1 from P. putida tesB+ cultured at 32 °C in LB medium periodically supplemented with glucose and levulinate. The highest 3HV titer obtained was 5.3 ± 0.1 g L−1 in M9 minimal medium supplemented with glucose and levulinate.