Transcription Factor ArcA is a Flux Sensor for the Oxygen Consumption Rate in <i>Escherichia coli</i>
Naoya Nochino, Yoshihiro Toya, Hiroshi Shimizu
Abstract
Abstract Oxygen supply is one of the major factors determining the metabolic state in microorganisms, and it affects the productivity of various compounds during bioproduction. In Escherichia coli ( E. coli ), the expression levels of numerous metabolic genes are regulated by transcription factors in response to changes in environmental oxygen conditions. Even at a same dissolved oxygen concentration, the amount of available oxygen changes depending on the oxygen transfer coefficient. However, it is not known whether E. coli is able to sense differences in the oxygen consumption rate. Therefore, the present study, is focused on the role of the transcription factor ArcA in the oxygen response of E. coli and investigated the relationship between ArcA activity and the oxygen consumption rate. To evaluate the activity of ArcA, a sensor plasmid expressing fluorescent protein under the control of the icd promoter, which is regulated by ArcA, is designed. E. coli containing the sensor plasmid is grown in continuous cultures with different oxygen supplies under different dilution rates. Although there is no correlation between ArcA activity and dissolved oxygen concentration, a strong negative correlation between ArcA activity and the specific oxygen consumption rate ( R 2 > 0.93) is observed.