As is known to all, negative feedback and time lag can cause oscillation in a pure physical system, such as sounds formed by oscillating air molecules and ripples produced via stirring water. What if the particles of wave are bacteria? In this project, we want to utilize a biological system with the properties of negative feedback and time-lapse to form a macroscopic wave-like pattern that could be visualized by the naked eye. Which the system is made by two parts: the light generator and the light sensor. When the light, which generated by the light generator, is strong enough that could be sensed by the light sensor. The sensor protein could repress the expression of light generator. This signal pathway, which based on light, makes the negative feedback. And the expression of light generator makes the time lag. We believe that with the limited spread of light on the colored plat medium, light output of the bacteria could make a biowave. This is the very first time that bacteria using light as an extracellular signal in synthetic biology. And the form of the oscillation pattern could help us explain a lot of biological problem, like the development of fingers and tones.

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