期刊
METABOLIC ENGINEERING
卷 45, 期 -, 页码 20-31出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.ymben.2017.11.006
关键词
High cell density; Halomonas bluephagenesis; Fermentation; vgb; Tat pathway; PHB; Polyhydroxyalkanoates; Halomonas; Synthetic biology
资金
- Ministry of Sciences and Technology [2016YFB0302504]
- National Natural Science Foundation of China [31430003]
- Tsinghua President Fund [2015THZ10]
Technologies enabling high-cell-density growth are required for economical industrial production of most biotechnological products. However, the key factor limiting cell density in bioreactors is the availability of oxygen during the late phases of fermentation. Although the expression of bacterial Vitreoscilla hemoglobin (VHb) is useful for enhanced oxygen availability, bacterial cell membrane makes efficient hemoglobin-oxygen contact a challenge. On the other hand, periplasmic spaces of Gram-negative microorganisms offer an excellent compartment for the intermittent storage of hemoglobin-bound oxygen. In this study, the cell growth was increased by a remarkable 100% using the twin-arginine translocase (Tat) pathway to export active VHb into the periplasm of Escherichia coli, Halomonas bluephagenesis TD01 and H. campaniensis LS21. Furthermore, eight low-oxygen-inducible vgb promoters were constructed in tandem to become a strong promoter cassette termed P-8vgb, which better induces expression of both gene vgb encoding VHb and the PHB synthesis operon microaerobically. Both the P-8vgb and VHb performed excellently in E. coli and two Halomonas spp., demonstrating their universal applicability for various organisms.
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