Space-Time Imaging of Bioluminescence from a Single Colony of Luminous Bacterium

We performed a space-time imaging analysis of a single colony of marine luminous bacterium using a fluorescent microscope connected to a real-color CCD camera. The bioluminescence and bright-field imaging showed that a glowing ring occurred close to the frontline of the growing colony, and that the ring spread out regularly while retaining a concentric ring shape. The glowing ring faded out when the colony terminated its growth. Furthermore, it was found that either aeration or O2-supply triggered a new glowing ring on the dim inside of the colony, and that the newly triggered ring phases out in the absence of aeration or O2-supply. Such a flickering pattern was confirmed to repetitively occur on the same concentric circle, corresponding to the presence and absence of aeration or O2-supply. From these findings, it is postulated that a growing single colony possesses a certain periodic property.