Improving the Availability of Oxygen to Achieve High Cell Density in Escherichia coli and Halomonas TD01 | AIChE

Improving the Availability of Oxygen to Achieve High Cell Density in Escherichia coli and Halomonas TD01

Authors 

Ouyang, P. - Presenter, Tsinghua University

Technology of high cell density fermentation is required for industrial production. However, the key factor limiting the cell high density is the shortage of oxygen at fermentation anaphase. It is urgent to develop a variety of oxygen utilization technology in order to increase the cell density of aerobic microorganisms in fermentation.

So far, there are mainly two strategies to increase cell density. One is the optimization of the oxygen utilization conditions in fermentation, while the other one is the update of microbial strains, which hold a better oxygen utilization efficiency by molecular modification. Expression of hemoglobin was a common choice. However, obstacles still existed against the inter-hemoglobin contacts. Therefore, it is a hotspot to increase the contact efficiency between hemoglobin and oxygen instead.

In the periplasmic space of microorganism, the oxygen could be captured by mature hemoglobin efficiently, which could reduce the transport loss of oxygen and increase the utilization efficiency. It is a possible way to increase the cell density. In our study, the cell density was significantly increased by 150% via using the twin-arginine translocase (Tat) pathway to export active Vitreoscilla hemoglobin to the periplasm in Escherichia coli and Halomonas TD01.