By Jason Matthews
Researchers discovered that bacteria, like most organisms on earth, have a circadian rhythm. This new understanding may have a significant impact on scientific research into drug delivery and biotech.
Research was done on the internal clocks of the non-photosynthetic soil bacterium called Bacillus Subtilis - Image Credit: Professor Ákos Kovács, Technical University of Denmark
What are circadian rhythms?
If you have ever suffered from jetlag or had to adjust to and from working night shifts, you know all too well how much your circadian rhythm affects both your mind and body. Circadian rhythm [or the day and night cycle] is vital for regulating normal body functions and overall health.
Almost every plant and animal on earth has a circadian rhythm. The 24hr cycle of light and temperature helps regulate and guide biological processes such as hormone release, sleep, water regulation, and other essential bodily functions. Disrupting this pattern causes organisms not to function well until the rhythm has had time to reset to the new routine.
Why is it important to understand how this affects bacteria?
Bacteria account for 12% of the planet's total biomass and are essential for the environment, human industry, and health of more complex life. In fact, without them, there would be no life. Yet we know little about their day-to-day cycle, or even if they follow one. That is until now.
Understanding if and how bacteria follow a circadian rhythm and how this benefits them is important. The knowledge may have a positive impact on the biotech industry, medicine, and food production. Research carried out between LMU (Ludwig Maximilians University) Munich, the John Innes Centre, and the Technical University of Denmark has shown that bacteria do indeed follow a circadian rhythm.
First study to find evidence of circadian rhythm in non-photosynthetic bacteria
The subject of the study was the non-photosynthetic soil bacterium Bacillus subtilis. The researchers employed a technique called luciferase reporting. This technique involves adding enzymes to the bacteria that produce bioluminescence so that the researchers could see the activation of specific genes. The two primary genes they were interested in are ytvA which encodes a blue light photoreceptor, and KinC involved in inducing biofilms and spores in the bacterium.
They compared the patterns of activation of the genes between two groups of Bacillus subtilis. The test group was kept in total darkness, and the control group was exposed to an equatorial day/night cycle [12 hours of light, 12 hours of darkness]. The researchers observed a regular pattern in the levels of ytvA among the bacteria exposed to the day/night cycle. However, the ytvA levels in the test group took several days to form a stable pattern. The researchers then swapped the groups, and the results were reversed, demonstrating the bacteria were able to adjust to their environmental time cues.
Image Credit: Dr_microbe via iStock/Getty images - HDR tune by Universal-Sci
The researchers carried out further experiments involving temperature variations and adjusting the light/dark cycles' length. The ytvA and KinC levels' patterns suggested a circadian rhythm and not just an on/off response to light and dark.
Professor Martha Merrow from LMU explains: "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."
Practical applications
This research helps us improve our understanding of circadian rhythms and how we may exploit this in bacteria. We may soon be able to answer such questions as; Does the time of day affect the likeliness or severity of infections? Do circadian rhythms affect the effectiveness of antibiotics? Can understanding circadian rhythms in bacteria improve areas of the biotech industries? Can this knowledge enhance food production and help protect crops from infection?
The author of the study, Dr Antony Dodd from the John Innes Centre, said, "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."
Professor Ákos Kovács, the co-author from the Technical University of Denmark, adds, "Bacillus subtilis is used in various applications from laundry detergent production to crop protection, besides recently exploiting as human and animal probiotics, thus engineering a biological clock in this bacterium will culminate in diverse biotechnological areas."
If you are interested in the details of the study, have a look at the research paper linked below.
Further reading:
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