(69e) Biological Production of Hydroxyacids from Renewable Sources

Hydroxyacids represent an important class of compounds that see application in the production of polyesters, biodegradable plastics and antibiotics, and they serve as useful chiral synthetic building blocks for other fine chemicals and pharmaceuticals. We have developed processes for the microbial production of one such class of hydroxyacids, the hydroxyvalerates. 4-hydroxyvalerate (4HV) and 3-hydroxyvalerate (3HV) are produced from the inexpensive and renewable carbon source levulinic acid utilizing an engineered strain of Pseudomonas putida. We tested two strains of P. putida: a commercially available strain (KT2440) and the PHA synthase knockout strain GPp104. We also examined two enzyme systems for removing CoA acyl carriers from intracellular hydroxyacids: the ptb/buk system and tesB. Once a suitable strain and enzyme system was found, the process was modulated at the shake flask scale in minimal and rich media for the high-titer production of both 3HV and 4HV. Maximum observable titers were 14 g/L for 4HV produced in rich medium and 5.3 g/L for 3HV produced in minimal medium. To our knowledge, this work represents the first time that hydroxyvalerates have been produced from a feasible feedstock in shake flasks at such high concentrations. This microbial system, as well as recombinant E. coli, are currently being investigated for their potential to produce other, longer chain hydroxyacids at high titers.