Lignin conversion to β-ketoadipic acid by Pseudomonas putida via metabolic engineering and bioprocess development

Abstract

Bioconversion of a heterogeneous mixture of lignin-related aromatic compounds (LRCs) to a single product via microbial biocatalysts is a promising approach to valorize lignin. Here, Pseudomonas putida KT2440 was engineered to convert mixed p-coumaroyl– and coniferyl-type LRCs to β-ketoadipic acid, a precursor for performance-advantaged polymers. Expression of enzymes mediating aromatic O -demethylation, hydroxylation, and ring-opening steps was tuned, and a global regulator was deleted. β-ketoadipate titers of 44.5 and 25 grams per liter and productivities of 1.15 and 0.66 grams per liter per hour were achieved from model LRCs and corn stover-derived LRCs, respectively, the latter representing an overall yield of 0.10 grams per gram corn stover-derived lignin. Technoeconomic analysis of the bioprocess and downstream processing predicted a β-ketoadipate minimum selling price of $2.01 per kilogram, which is cost competitive with fossil carbon-derived adipic acid ($1.10 to 1.80 per kilogram). Overall, this work achieved bioproduction metrics with economic relevance for conversion of lignin-derived streams into a performance-advantaged bioproduct.

Economic and Environmental Trade-Offs of Simultaneous Sugar and Lignin Utilization for Biobased Fuels and Chemicals

“…Toxicity to the microbial conversion platform will vary from strain to strain, where microbes such as R. toruloides have an innate high tolerance to such compounds due to native degradation pathways. Using engineering routes, it may be possible to integrate such existing catabolism or degradation steps into the conversion pathway, 66,72 thus maintaining (or enhancing) the microbe's innate tolerance while also providing biosynthetic routes to convert the aromatic to the final product. Our findings indicate that a lignin-to-bisabolene conversion of 36− 66 wt % is necessary to achieve cost-parity with the baseline market price of diesel in 2050, which is $1.1/L (2022$).…”

Programmable marine bacteria catalyze the valorization of lignin monomers

“…Innovations for the valorization of lignin are imperative and urgent. Given the revolutionary advances in engineering biology, bioconversion of ligninderived aromatic compounds to value-added chemicals, e.g., cis,cis-muconic acids, pyridine-dicarboxylic acids and b-ketoadipic acids, has been achieved in engineered Pseudomonas putida (7)(8)(9), Corynebacterium glutamicum (10) and Rhodococcus jostii (11), illustrating a promising avenue for the sustainable valorization of lignin-derived aromatics.…”

Full use of lignocellulosic biomass for efficient synthesis of l-tyrosine and its analogues by engineering microbial consortia

“…21–24 Through simple genetic modifications, these microorganisms could convert lignin hydrolysate and lignin-derived aromatics into many value-added chemicals, such as cis , cis -muconic acid, 25 pyridine-2,4-dicarboxylic acid, 26 gallate, 22 β-ketoadipic acid, polyhydroxyalkanoates (PHAs), and lipids. 21,27 Alternatively, synthetic biology allows for the engineering of microorganisms ( e.g. , Escherichia coli ) that do not naturally metabolize lignin to convert lignin-derived aromatics to value-added products, 14,28–31 including vanillin, 4-hydroxyphenylacetic acid, l -tyrosine 32–34 and bioactive substances ( e.g.…”