Xylose-negative Corynebacterium glutamicum has been engineered to utilize xylose as the sole carbon source via either the xylose isomerase (XI) pathway or the Weimberg pathway. Heterologous expression of xylose isomerase and overexpression of a gene encoding for xylulose kinase enabled efficient xylose utilization. In this study, we show that two functionally-redundant transcriptional regulators (GntR1 and GntR2) present on xylose repress the pentose phosphate pathway genes. For efficient xylose utilization, pentose phosphate pathway genes and a phosphoketolase gene were overexpressed with the XI pathway in C. glutamicum. Overexpression of the genes encoding for transaldolase (Tal), 6-phosphogluconate dehydrogenase (Gnd), or phosphoketolase (XpkA) enhanced the growth and xylose consumption rates compared to the wild-type with the XI pathway alone. However, co-expression of these genes did not have a synergetic effect on xylose utilization. For the succinate production from xylose, overexpression of the tal gene with the XI pathway in a succinate-producing strain improved xylose utilization and increased the specific succinate production rate by 2.5-fold compared to wild-type with the XI pathway alone. Thus, overexpression of the tal, gnd, or xpkA gene could be helpful for engineering C. glutamicum toward production of value-added chemicals with efficient xylose utilization.
Bibliographical noteFunding Information:
The authors would like to thank Prof. Dr. Michael Bott and Juniorprof. Dr. Julia Frunzke at Forschungszentrum Jülich for providing C. glutamicum ΔgntR1, ΔgntR2, and ΔgntR1ΔgntR2 mutants and BL-1. This work was supported by a National Research Council of Science & Technology (NST) grant by the Korea government (MSIP) (No. CAP-11-04-KIST). Also, this work was partially supported by a Golden Seed Project (213008-05-1-WT911) grant funded by the Ministry of Agriculture, Ministry of Oceans and Fisheries.
© 2017 Elsevier B.V.
- Corynebacterium glutamicum
- Metabolic engineering
- Synthetic biology
- Xylose utilization
ASJC Scopus subject areas
- Applied Microbiology and Biotechnology