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- Title
Metabolic engineering of Corynebacterium glutamicum for the production of cis , cis -muconic acid from lignin.
- Authors
Becker, Judith; Kuhl, Martin; Kohlstedt, Michael; Starck, Sören; Wittmann, Christoph
- Abstract
Background: Cis , cis -muconic acid (MA) is a dicarboxylic acid of recognized industrial value. It provides direct access to adipic acid and terephthalic acid, prominent monomers of commercial plastics. Results: In the present work, we engineered the soil bacterium Corynebacterium glutamicum into a stable genome-based cell factory for high-level production of bio-based MA from aromatics and lignin hydrolysates. The elimination of muconate cycloisomerase ( catB ) in the catechol branch of the β-ketoadipate pathway provided a mutant, which accumulated MA at 100% molar yield from catechol, phenol, and benzoic acid, using glucose as additional growth substrate. The production of MA was optimized by constitutive overexpression of catA , which increased the activity of the encoded catechol 1,2-dioxygenase, forming MA from catechol, tenfold. Intracellular levels of catechol were more than 30-fold lower than extracellular levels, minimizing toxicity, but still saturating the high affinity CatA enzyme. In a fed-batch process, the created strain C. glutamicum MA-2 accumulated 85 g L−1 MA from catechol in 60 h and achieved a maximum volumetric productivity of 2.4 g L−1 h−1. The strain was furthermore used to demonstrate the production of MA from lignin in a cascade process. Following hydrothermal depolymerization of softwood lignin into small aromatics, the MA-2 strain accumulated 1.8 g L−1 MA from the obtained hydrolysate. Conclusions: Our findings open the door to valorize lignin, the second most abundant polymer on earth, by metabolically engineered C. glutamicum for industrial production of MA and potentially other chemicals.
- Subjects
MUCONIC acid; DICARBOXYLIC acids; TEREPHTHALIC acid; CATECHOL; BENZOATES
- Publication
Microbial Cell Factories, 2018, Vol 17, Issue 1, pN.PAG
- ISSN
1475-2859
- Publication type
Article
- DOI
10.1186/s12934-018-0963-2