Effects of Lac operon activation, deletion of the Yhha gene, and the removal of oxygen on the ultra-weak photon emission of Escherichia coli.

We observed a relation between gene activity and ultra-weak photon emission (UPE). By comparing the UPEs of E. coli with the LacI gene present and deleted we found that more gene activity produced higher UPE. This relation was further confirmed by studying the UPE of the E. coli with and without the Yhha gene. We interpreted that a higher aminoacyl t-RNA synthetase activity, which used ATP from the respiratory chain, could increase the emission. Satisfying the increased need of ATP by the E. coli through an increase of respiratory chain activity, which has reactive oxygen species (ROS) as a byproduct, results in a higher rate of photon emission. To ensure that oxygen is at the origin of this emission, we replaced the air by pure nitrogen. After 30 min, it was observed that the emission levels equaled the emission levels of the sterile medium. We could therefore conclude that the source of the photon emission would be affected by genetic activity and is oxygen related.