Journal
METABOLIC ENGINEERING
Volume 28, Issue -, Pages 240-247Publisher
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.ymben.2015.01.005
Keywords
Lignin valorization; beta-ketoadipate pathway; Aromatic degradation; Pseudomonas putida KT2440; Sphingobium sp strain SYK-6
Categories
Funding
- US Department of Energy BioEnergy Technologies Office
Ask authors/readers for more resources
Lignin represents an untapped feedstock for the production of fuels and chemicals, but its intrinsic heterogeneity makes lignin valorization a significant challenge, In nature, many aerobic organisms degrade lignin-derived aromatic molecules through conserved central intermediates including catechol and protocatechuate. Harnessing this microbial approach offers potential for lignin upgrading in modern biorefineries, but significant technical development is needed to achieve this end. Catechol and protocatechuate are subjected to aromatic ring cleavage by dioxygenase enzymes that, depending on the position, ortho or meta relative to adjacent hydroxyl groups, result in different products that are metabolized through parallel pathways for entry into the TCA cycle. These degradation pathways differ in the combination of succinate, acetyl-CoA, and pyruvate produced, the reducing equivalents regenerated, and the amount of carbon emitted as CO2 factors that will ultimately impact the yield of the targeted product. As shown here, the ring-cleavage pathways can be interchanged with one another, and such substitutions have a predictable and substantial impact on product yield. We demonstrate that replacement of the catechol ortho degradation pathway endogenous to Pseudomonas putida KT2440 with an exogenous meta-cleavage pathway from P. putida mt-2 increases yields of pyruvate produced from aromatic molecules in engineered strains. Even more dramatically, replacing the endogenous protocatechuate ortho pathway with a meta-cleavage pathway from Sphingobium sp. SYK-6 results in a nearly five-fold increase in pyruvate production. We further demonstrate the aerobic conversion of pyruvate to L-lactate with a yield of 41.1 +/- 2.66 (wt/wt), Overall, this study illustrates how aromatic degradation pathways can be tuned to optimize the yield of a desired product in biological lignin upgrading. (C) 2015 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved,
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available