Increasing oxygen availability for improving poly(3-hydroxybutyrate) production by Halomonas

• Published in: Metabolic engineering Vol. 45; pp. 20 - 31
• Main Authors: Ouyang, Pengfei, Wang, Huan, Hajnal, Ivan, Wu, Qiong, Guo, Yingying, Chen, Guo-Qiang
• Format: Journal Article
• Language: English
• Published: Belgium Elsevier Inc 01.01.2018
• Subjects: Bacterial Proteins - biosynthesis; Bacterial Proteins - genetics; Fermentation; Halomonas; Halomonas - genetics; Halomonas - metabolism; Halomonas bluephagenesis; High cell density; Hydroxybutyrates - metabolism; Oxygen - metabolism; Oxygen Consumption; PHB; Polyesters - metabolism; Polyhydroxyalkanoates; Synthetic biology; Tat pathway; Truncated Hemoglobins - biosynthesis; Truncated Hemoglobins - genetics; vgb; Vitreoscilla - genetics; vgb; Halomonas; Halomonas bluephagenesis; Synthetic biology; Tat pathway; PHB; Fermentation; Polyhydroxyalkanoates; High cell density
• ISSN: 1096-7176; 1096-7184
• DOI: 10.1016/j.ymben.2017.11.006

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 P8vgb, which better induces expression of both gene vgb encoding VHb and the PHB synthesis operon microaerobically. Both the P8vgb and VHb performed excellently in E. coli and two Halomonas spp., demonstrating their universal applicability for various organisms. •P8vgb was used to induce expressions of vgb under microaerophilic conditions.•A system for the periplasmic expression of functional VHb was established.•Periplasmic vgb expression resulted in better growth of Halomonas.•Periplasmic expression of vgb improves oxygen availability.