Bacteria Have Internal Clocks Just Like Humans, Scientist Confirm

It turns out that non-photosynthetic bacteria can tell the time.
Derya Ozdemir

A team of international researchers has answered a long-standing biological question: Much like animals and plants, bacteria have internal clocks that align with the 24-hour cycle of life on Earth and are regulated by the same circadian rhythms.

This is a first-of-its-kind discover since while bacteria represent 12% biomass of the planet, scientists didn't know much about their biological clocks. While previous studies had shown that photosynthetic bacteria have biological clocks, much wasn't known about the free-living non-photosynthetic bacteria in this regard.

Now, however, researchers have detected free-running circadian rhythms in the non-photosynthetic soil bacterium Bacillus subtilis, which is used in numerous applications from laundry detergent production to crop protection, by utilizing a technique called luciferase reporting. This enzyme basically enables researchers to see how active a gene is inside an organism when added, resulting in the reported discovery.

The study was published in Science Advances.

A cycle was observed even in constant darkness

By focusing on two genes called ytvA, which encodes a blue-light photoreceptor, and an enzyme called KinC, which is involved in inducing the formation of biofilms and spores in the bacterium; they were able to observe the levels of the genes in the constant dark in comparison to cycles of 12 hours of light and 12 hours of dark.

It turned out that the pattern of ytvA levels was adjusted to the light and dark cycle. Levels increased during the dark and decreased in the light. Moreover, a cycle was still observed in constant darkness.

Professor Martha Merrow from the Ludwig Maximilians University, Munich, who is the lead author of the study, stated, "We've found for the first time that non-photosynthetic bacteria can tell the time. They adapt their molecular workings to the time of day by reading the cycles in the light or in the temperature environment."

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"In addition to medical and ecological questions, we wish to use bacteria as a model system to understand circadian clock mechanisms. The lab tools for this bacterium are outstanding and should allow us to make rapid progress," she stated.


This study could have implications for the timing of drug delivery, biotechnology, and how we develop timely solutions for crop protection. author Dr. Antony Dodd from the John Innes Centre says, "Our study opens doors to investigate circadian rhythms across bacteria. Now that we have established that bacteria can tell the time we need to find out the processes that cause these rhythms to occur and understand why having a rhythm provides bacteria with an advantage."

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