Document Type : Research Paper
Authors
1
Program in Biotechnology, Faculty of Science, Chulalongkorn University, Phayathai Road, Patumwan, Bangkok 10330, Thailand.
2
Department of Materials Science and Engineering, Institute of Science Tokyo, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan.
3
Department of Microbiology, Faculty of Science, Chulalongkorn University, Phayathai Road, Patumwan, Bangkok 10330, Thailand.
4
International Center for Biotechnology, The University of Osaka, Suita, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
Abstract
The biomaterial polyhydroxybutyrate (PHB) is a promising, renewable, and green alternative polymer. In this study, a method to incorporate gluconate 6-phosphate dehydratase (edd) deletion in Escherichia coli expressing PHB biosynthesis genes from Cupriavidus necator strain A-04 was proposed. The growth of the edd-deficient strain, which is defective in the glycolytic Entner–Doudoroff pathway, decreased significantly in Luria-Bertani (LB) medium supplemented with glucose. Surprisingly, compared with the wild-type strain, the recombinant edd-deficient strain expressing PHB biosynthesis genes exhibited expeditious PHB accumulation with a high PHB content. The edd-deficient strain reached the highest PHB concentration of 7.6 g/L and a 93 wt% PHB content within 30 h of flask-scale cultivation when commercial glucose was used as the sole carbon source. In addition, the resulting strain was able to utilize crude glycerol waste from the biodiesel industry for PHB accretion with a 74.8 wt% content in 24 h. The PHB yields obtained from glucose and crude glycerol waste were 0.37 and 0.20 g PHB/g substrate, respectively. These findings not only broaden the understanding of the effect of glucose metabolism on PHB production but also provide promising candidates for the production of polyhydroxyalkanoates in the future.
Graphical Abstract
Highlights
- ∆edd in E. coli led to the accumulation of 93 wt% PHB produced from glucose in 30 h.
- E. coli ∆edd-pBSK-CABA-04 achieved 7.6 g/L PHB with a 0.37 g/g yield from glucose.
- E. coli ∆edd-pBSK-CABA-04 utilized crude glycerol to produce 74.8 wt% PHB in 24 h.
- The PHB yield reached 0.37 g/g from glucose and 0.20 g/g from crude glycerol.
- ∆edd in E. coli redirected carbon flux and enhanced PHB biosynthetic efficiency.
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