Presentation Information
[P02-283]Microbial Lignin Valorization using Engineered Pseudomonas taiwanensis VLB120
○Priyadharshini T1, Vishnu Prasad J1, Guhan Jayaraman1 (1. Indian Institute of Technology Madras (India))
Keywords:
Lignin valorization,cis,cis-Muconic acid,Pseudomonas taiwanensis VLB120,Protocatechuic acid,p-Coumarate enrichment
Lignin-based biorefineries offer a sustainable alternative for the production of platform chemicals traditionally derived from fossil fuels. The depolymerization of lignin yields diverse aromatic monomers that serve as promising renewable feedstocks for the microbial production of biochemicals. However, efficient microbial valorization of depolymerized lignin streams is often constrained by low recovery of lignin-derived monomers, the formation of microbial growth inhibitors during pretreatment, and limitations in microbial metabolic capacity. Therefore, in order to overcome these challenges, it is essential to focus on integrated strategies: Developing lignin depolymerization methods that selectively enrich aromatic monomers while reducing microbial toxicity, and strain engineering to develop robust strains for efficient microbial upcycling of obtained lignin-derived monomers.
In this study, we present an integrated lignin biorefinery scheme for the bioconversion of biomass-derived p-coumarate using engineered Pseudomonas taiwanensis VLB120. Previous work in our lab improved the wild-type strain’s tolerance and uptake of p-coumarate by strain engineering and adaptive laboratory evolution. This strain can be engineered as a potent microbial chassis for producing industrially valuable chemicals via the β-ketoadipate pathway. Targeted deletion of the protocatechuate 3,4-dioxygenase gene (pcaHG) resulted in the accumulation of protocatechuate, a versatile chemical used in the pharmaceutical, food, and polymer industries. Through optimized feeding strategies in the bioreactor, we achieved protocatechuate titre of 140 mM from synthetic p-coumarate, with a yield of 0.92 mol/mol – representing the highest titre reported to date. Subsequent identification of rate-limiting steps guided further strain engineering to enhance productivity. The strain was further engineered to produce cis,cis-muconic acid, a platform chemical and biopolymer precursor. Shake flask studies resulted in the muconic acid titre of 40 mM from synthetic p-coumarate. This demonstrates the versatility of the bacteria as a microbial chassis for p-coumarate valorization.
To extend the production from biomass-derived substrates, p-coumarate was recovered from corncob using alkali pretreatment at optimized conditions. Alkali-pretreated liquor was further processed to enrich p-coumarate by removing high-molecular-weight lignin and salts, thereby improving bioconversion efficiency. In the preliminary flask study, the engineered strain produced 40 mM of protocatechuate and 40 mM of muconic acid from the p-coumarate-enriched fraction. Future work will focus on process optimization to improve product titres and production rate from biomass-derived p-coumarate, thus establishing P. taiwanensis VLB120 as a robust platform strain for sustainable lignin-based biomanufacturing.
In this study, we present an integrated lignin biorefinery scheme for the bioconversion of biomass-derived p-coumarate using engineered Pseudomonas taiwanensis VLB120. Previous work in our lab improved the wild-type strain’s tolerance and uptake of p-coumarate by strain engineering and adaptive laboratory evolution. This strain can be engineered as a potent microbial chassis for producing industrially valuable chemicals via the β-ketoadipate pathway. Targeted deletion of the protocatechuate 3,4-dioxygenase gene (pcaHG) resulted in the accumulation of protocatechuate, a versatile chemical used in the pharmaceutical, food, and polymer industries. Through optimized feeding strategies in the bioreactor, we achieved protocatechuate titre of 140 mM from synthetic p-coumarate, with a yield of 0.92 mol/mol – representing the highest titre reported to date. Subsequent identification of rate-limiting steps guided further strain engineering to enhance productivity. The strain was further engineered to produce cis,cis-muconic acid, a platform chemical and biopolymer precursor. Shake flask studies resulted in the muconic acid titre of 40 mM from synthetic p-coumarate. This demonstrates the versatility of the bacteria as a microbial chassis for p-coumarate valorization.
To extend the production from biomass-derived substrates, p-coumarate was recovered from corncob using alkali pretreatment at optimized conditions. Alkali-pretreated liquor was further processed to enrich p-coumarate by removing high-molecular-weight lignin and salts, thereby improving bioconversion efficiency. In the preliminary flask study, the engineered strain produced 40 mM of protocatechuate and 40 mM of muconic acid from the p-coumarate-enriched fraction. Future work will focus on process optimization to improve product titres and production rate from biomass-derived p-coumarate, thus establishing P. taiwanensis VLB120 as a robust platform strain for sustainable lignin-based biomanufacturing.
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