Format

Send to

Choose Destination
Appl Microbiol Biotechnol. 2019 Apr;103(8):3381-3391. doi: 10.1007/s00253-019-09737-8. Epub 2019 Mar 15.

Metabolic engineering of Corynebacterium glutamicum for hyperproduction of polymer-grade L- and D-lactic acid.

Author information

1
Research Institute of Innovative Technology for the Earth, 9-2, Kizugawadai, Kizugawa, Kyoto, 619-0292, Japan.
2
Institute for Frontier Science Initiative, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan.
3
Research Institute of Innovative Technology for the Earth, 9-2, Kizugawadai, Kizugawa, Kyoto, 619-0292, Japan. mmg-lab@rite.or.jp.
4
Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara, 630-0101, Japan. mmg-lab@rite.or.jp.

Abstract

Strain development is critical for microbial production of bio-based chemicals. The stereo-complex form of polylactic acid, a complex of poly-L- and poly-D-lactic acid, is a promising polymer candidate due to its high thermotolerance. Here, we developed Corynebacterium glutamicum strains producing high amounts of L- and D-lactic acid through intensive metabolic engineering. Chromosomal overexpression of genes encoding the glycolytic enzymes, glucokinase, glyceraldehyde-3-phosphate dehydrogenase, phosphofructokinase, triosephosphate isomerase, and enolase, increased L- and D-lactic acid concentration by 146% and 56%, respectively. Chromosomal integration of two genes involved in the Entner-Doudoroff pathway (6-phosphogluconate dehydratase and 2-dehydro-3-deoxyphosphogluconate aldolase), together with a gene encoding glucose-6-phosphate dehydrogenase from Zymomonas mobilis, to bypass the carbon flow from glucose, further increased L- and D-lactic acid concentration by 11% and 44%, respectively. Finally, additional chromosomal overexpression of a gene encoding NADH dehydrogenase to modulate the redox balance resulted in the production of 212 g/L L-lactic acid with a 97.9% yield and 264 g/L D-lactic acid with a 95.0% yield. The optical purity of both L- and D-lactic acid was 99.9%. Because the constructed metabolically engineered strains were devoid of plasmids and antibiotic resistance genes and were cultivated in mineral salts medium, these strains could contribute to the cost-effective production of the stereo-complex form of polylactic acid in practical scale.

KEYWORDS:

Corynebacterium glutamicum; Entner–Doudoroff pathway; Glycolytic enzymes; Lactic acid; Metabolic engineering

PMID:
30877357
DOI:
10.1007/s00253-019-09737-8
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Springer
Loading ...
Support Center