In the first-of-its-kind discovery, scientists have confirmed that the bacteria have a 24-hour body clock


In a first-of-its-kind discovery, scientists have found that a species of non-photosynthetic bacteria is regulated by a single circadian rhythm that dominates so many other life-forms.

In humans, our circadian rhythms act as a kind of biological clock in our cells, controlling almost all the processes in our bodies that affect the functioning of our metabolic and cognitive processes when we sleep and wake up. We do.

This internal time-keeping, which rotates in a cycle of approximately 24 hours, is driven by our circadian clock, and a similar main event has been observed in many other types of organisms, including organisms, plants, and fungi.

For a long time, however, it is unclear whether large-scale bacteria are also subject to orders of circadian rhythms.

This phenomenon has been demonstrated in photosynthetic bacteria, which use light to create chemical energy, but as to whether other types of bacteria also remain a longtime mystery of circadian clocks – until now.

“We have found for the first time that non-photosynthetic bacteria can tell time,” explains chronobiologist Martha Merrow from Ludwig Maximilian University in Munich.

“They optimize their molecular functioning for the time of day by reading cycles in light or temperature environments.”

In a new study, Marrow and fellow researchers investigated Bacillus subtilis, A hardy, well-studied bacterium found in soil and the gastrointestinal tract of many animals, including humans.

whereas B. Subtillis Not photosynthetic, it is sensitive to light for photoreceptors, and previous observations of the microbe have indicated that its gene activity and biofilm formation processes may follow a diurnal cycle in response to environmental cues, perhaps light levels. Or depending on the change in temperature.

To investigate, researchers measured the gene expression activity of bacteria in cultures exposed to an alternating daily cycle of 12 hours of light to continuous darkness or 12 hours of light.

In the alternating light / dark cycle, expression of a gene called ytvA – which encodes a blue light photoreceptor – increased during the dark phase and decreased during the light phase, indicating processes of entry into a circadian clock. .

When under constant darkness, the cycle still existed B. Subtillis, Although the duration became longer, not strictly following the 24-hour cycle without the light signal.

In another experiment, researchers experimented with temperature cycles, which is another way to encourage heat changes between day and night.

Again, the expression of ytvA as emitted and temperature is cycled between 12 hours at 25.5 ° C (77.9 ° F) and 12 hours at 28.5 ° C (83.3 ° F), and, with light, the cycle is a free The iteration remains in the experiment (not synchronized for environmental cues) though with a longer duration.

Taking all the results together, the researchers concluded B. Subtillis There is a circadian clock, which is characterized by a free-moving circadian rhythm and systematic penetration of environmental signals known as the Ziegtber cycle.

While the findings so far relate to only one bacterial species, this is the first time that this phenomenon has occurred in any non-photosynthetic bacteria, which may have broad implications for our overall understanding of bacteria: Organisms that account for about 15 percent of living matter on Earth.

“Our study opens doors to the investigation of circadian rhythm in bacteria,” says Antony Dodd, a circadian rhythm researcher at the John Innes Center in the UK.

“Now that we have established that non-photosynthetic bacteria can indicate the need of the hour to detect the processes that occur in bacteria, which produce these rhythms, and understand why the bacteria with an advantage is the rhythm. Provides. “

For now, the team hypothesized that the circadian rhythm may be regulated by any transcriptional-translational feedback system, or that it may be linked to metabolic cycles.

It is also unknown whether a form of the overall ‘master clock’ can be controlled in some way B. SubtillisCircadian time-keeping has been suggested in humans, although the team suggests this is a possibility.

“It would be informative to check whether temperature and light are the inputs of a master pacemaker B. Subtillis There are many types of unicellular, as described for different types of unicellular and multicellular organisms, ”the authors write in their paper.

“It is also possible that B. Subtillis There may be either a master oscillator or one or more downstream oscillators coupled and entered by a main pacemaker. “

In any case, the effects of a 24-hour body clock in bacteria can lead to heavy panacea – not only in terms of scientific understanding of bacterial biology, but also in its potential use in biomedical science, agriculture, industry and beyond.

Bacillus subtilis Laundry detergents are used in various applications from production to crop protection … [and] Human and animal probiotics, ”says bioengineer Kkos Kovacs from the Technical University of Denmark.

“Thus engineering a biological clock in this bacterium will culminate in diverse biotechnological fields.”

The findings are stated in Science advance.

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