Engineered C. glutamicum strain capable of producing high-level glutaric acid from glucose

November 16, 2020

A metabolic engineering research group at KAIST has developed an engineered Corynebacterium glutamicum strain capable of producing high-level glutaric acid without byproducts from glucose. This new strategy will be useful for developing engineered microorganisms for the bio-based production of value-added chemicals.

Glutaric acid, also known as pentanedioic acid, is a carboxylic acid that is widely used for various applications including the production of polyesters, polyamides, polyurethanes, glutaric anhydride, 1,5-pentanediol, and 5-hydroxyvaleric acid. Glutaric acid has been produced using various petroleum-based chemical methods, relying on non-renewable and toxic starting materials. Thus, various approaches have been taken to biologically produce glutaric acid from renewable resources. Previously, the development of the first glutaric acid producing Escherichia coli by introducing Pseudomonas putida genes was reported by a research group from KAIST, but the titer was low. Glutaric acid production by metabolically engineered Corynebacterium glutamicum has also been reported in several studies, but further improvements in glutaric acid production seemed possible since C. glutamicum has the capability of producing more than 130 g/L of L-lysine.

A research group comprised of Taehee Han, Gi Bae Kim, and Distinguished Professor Sang Yup Lee of the Department of Chemical and Biomolecular Engineering addressed this issue. Their research paper "Glutaric acid production by systems metabolic engineering of an L-lysine-overproducing Corynebacterium glutamicum" was published online in PNAS on November 16, 2020.

This research reports the development of a metabolically engineered C. glutamicum strain capable of efficiently producing glutaric acid, starting from an L-lysine overproducer. The following novel strategies and approaches to achieve high-level glutaric acid production were employed. First, metabolic pathways in C. glutamicum were reconstituted for glutaric acid production by introducing P. putida genes. Then, multi-omics analyses including genome, transcriptome, and fluxome were conducted to understand the phenotype of the L-lysine overproducer strain. In addition to systematic understanding of the host strain, gene manipulation targets were predicted by omics analyses and applied for engineering C. glutamicum, which resulted in the development of an engineered strain capable of efficiently producing glutaric acid. Furthermore, the new glutaric acid exporter was discovered for the first time, which was used to further increase glutaric acid production through enhancing product excretion. Last but not least, culture conditions were optimized for high-level glutaric acid production. As a result, the final engineered strain was able to produce 105.3 g/L glutaric acid, the highest titer ever reported, in 69 hours by fed-batch fermentation.

Professor Sang Yup Lee said, "It is meaningful that we were able to develop a highly efficient glutaric acid producer capable of producing glutaric acid at the world's highest titer without any byproducts from renewable carbon sources. This will further accelerate the bio-based production of valuable chemicals in pharmaceutical/medical/chemical industries."
Taehee Han, Gi Bae Kim, and Sang Yup Lee. Glutaric acid production by systems metabolic engineering of an L-lysine-overproducing Corynebacterium glutamicum. PNAS.

This research was supported by the Bio & Medical Technology Development Program of the National Research Foundation (Grant 2020M3A9I503788311) and funded by the Ministry of Science and ICT, Republic of Korea.

-About KAIST
KAIST is the first and top science and technology university in Korea. KAIST was established in 1971 by the Korean government to educate scientists and engineers committed to the industrialization and economic growth of Korea.

Since then, KAIST and its 64,739 graduates have been the gateway to advanced science and technology, innovation, and entrepreneurship. KAIST has emerged as one of the most innovative universities with more than 10,000 students enrolled in five colleges and seven schools including 1,039 international students from 90 countries. On the precipice of its semi-centennial anniversary in 2021, KAIST continues to strive to make the world better through the pursuit in education, research, entrepreneurship, and globalization.

The Korea Advanced Institute of Science and Technology (KAIST)

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