Bioconversion of lignin-derived aromatics into the building block pyridine 2,4-dicarboxylic acid by engineering recombinant Pseudomonas putida strains
Helena Gómez‐Álvarez, Pablo Iturbe, Virginia Rivero‐Buceta, Paul D. Mines, Timothy D. H. Bugg, Juan Nogales, Eduardo Dı́az
Abstract
2,4 pyridine dicarboxylic acid (2,4 PDCA) is an analogue of terephthalate, and hence a target chemical in the field of bio-based plastics. Here, Pseudomonas putida KT2440 strains were engineered to efficiently drive the metabolism of lignin-derived monoaromatics towards 2,4 PDCA in a resting cells-based bioprocess that alleviates growth-coupled limitations and allows biocatalysts recycling. Native β-ketoadipate pathway was blocked by replacing protocatechuate 3,4-dioxygenase by the exogenous LigAB extradiol dioxygenase. Overexpression of pcaK encoding a transporter increased 8-fold 2,4 PDCA productivity from protocatechuate, reaching the highest value reported so far (0.58 g L-1h−1). Overexpression of the 4-hydroxybenzoate monooxygenase (pobA) speed up drastically the production of 2,4 PDCA from 4-hydroxybenzoate (0.056 g L-1h−1) or p-coumarate (0.012 g L-1h−1) achieving values 15-fold higher than those reported with Rhodococcus jostii biocatalysts. 2,4 PDCA was also bioproduced by using soda lignin as feedstock, paving the way for future polymeric lignin valorization approaches.