Scientists discovered unusual activity in dormant bacteriaspores. This is the first evidence that the organisms still have a sense of their surroundings, even though they are physiologically dead.
Instead of using their usual fuel, bacteria could respond to small changes in nutrients to determine when it is prime time to wake up.
This discovery will challenge our understanding of disease and the possibility that life could survive in extreme conditions on Earth.
“This work changes how we think about spores. Previously, they were thought to be inert objects.” says molecular biologist and lead researcher Gürol SüelUniversity of California San Diego
“We have shown that cells can process information even when they are deeply dormant.” We found that spores can use their stored electrochemical potential energy without any metabolic activity to compute their environment.
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The implications also spread beyond disease management here on Earth – it’s often thought that one way we may encounter extraterrestrial life is in similar dormant states.
“If scientists find that life is possible, MarsOder VenusIt is most likely that it is in a dormant condition and we now know that an inert life form may still be capable to think about its next steps.” Says Süel.
Bacteria are generally pretty tough, but one of their key survival tactics is being able to shut down into spores, where they can remain in a dehydrated, dormant state surrounded by a protective coating for hundreds of years – surviving extreme heat, pressure, and even outer space.
This isn’t a deep sleep. The bacteria is physiologically dead with no metabolism.
They know when the right conditions exist to get up again.
Spores are the result of diseases like anthrax that were caused by the Bacillus anthracis bacteria, can survive long periods without water or nutrients in the mail – within moments of exposure to suitable conditions, they’re able to rehydrate and restart their metabolism, allowing them to become infectious again.
But how do spores actually know when they need to wake up? If good times end soon, it could be a waste of energy to respond to every drop or whiff nutrient. But, waiting for the feast could also lead to missed opportunities.
To tease this out further, Süel and his team tested thousands of dormant Bacillus subtilis spores. These bacteria are non-harmful to people and can also be found in the environment. Keep the recordFor the longest period of time, living in space.
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They measured whether the spores could pick up on multiple short-lived pulses of nutrients being sent into their environment – signals that generally wouldn’t be strong enough to trigger a spore to come back to life.
It was not enough to get the bacteria awakened by just one or two nutrient pulses, as predicted. Over time, however, it seemed that a cumulative effect began to take place; the bacteria were somehow able keep track and switch back on after a certain number signals.
The team was also capable of monitoring changes in the activity in response to short-lived signals. It showed that bacteria were using stored energie in the form potassium ions (K).+With each input, ),
This works in the same way as a capacitor, which stores energy for later use.
The team used a mathematical model to explain the phenomenon. Over time, the potassium ions became stronger enough to trigger the reawakening. This was called “a miracle.”integrate-and-fire“Activation Model”
This is known as a cumulative signals processing strategy. If conditions are not right, it prevents the bacteria from awakening too quickly.
“These findings reveal a decision making mechanism that works in physiologically inactive cells.” The researchers wrote in their paper.
This is an evolutionary strategy that is familiar in some ways.
“The way that spores receive information is the same as how neurons function in our brains,” Says Süel.
“Both bacteria and neurons use small and long inputs to determine when a threshold has been reached. The threshold is reached when spores return to normal. When this happens, neurons release an action potential that allows them to communicate with other neurons.
But unlike neurons, which require a lot of energy, the spores could do this without any metabolic energy, but only the stored potassium.
The following is an accompanying Perspectives pieceJonathan Lombardino from the University of Wisconsin Madison and Briana Burton, microbiologists, say further research with other organisms that can enter a similar spore state to yeast could help us understand this more broadly.
“For instance, could the superdormant spores have an unusual longevity due to high K+ concentrations? They write.
There’s more work to be done, but the discovery challenges our understanding of dormant bacteria as being inert – and also reframes how we may evaluate signs of extraterrestrial life in the future.
The research was published in Science.
