Bacteria that go into torpor, becoming physiologically dead, if the conditions are hostile and, if the environment improves, they ‘resurrect’ and become active bacteria again. What a team of scientists have just discovered when they see how, when faced with extreme conditions such as hunger and stress, some bacteria enter a dormant state in which vital processes stop, is how they reactivate themselves. They turn into ‘zombie’ bacteria, initially, but it turns out that these bacteria evaluate the environmental conditions for the return to life. If the environment is conducive again, they decide to “come back to life ”. This important finding would have implications for evaluating life on Earth and other planets.
The process of a zombie bacteria
Some bacteria enter a dormant state in which their vital functions cease when exposed to starvation and stressful conditions . If it’s a bad time to be alive, they stop their life processes and in this state, these cells, known as spores , can withstand the extreme punishments of heat, pressure, and even the harsh conditions of space by going into deep hibernation. They could remain in this dormant state for thousands of years and be reactivated in a matter of minutes when the right circumstances arise.
How do bacteria do it? Using a stored supply of charged particles for power, instead of their usual fuel; the bacteria can thus actively respond to small changes in nutrient levels to determine an optimal time to wake up. A new proof of how life could make its way in extreme places not only here on Earth, but on other planets.
“This work changes the way we think about spores, which were considered inert objects ,” says molecular biologist and principal investigator Gürol Süel of the University of California, San Diego and co-author of the paper published in the journal Science. “We showed that cells in a deeply dormant state have the ability to process information. We found that spores can release their stored electrochemical potential energy to perform a calculation on their environment without the need for metabolic activity.”
The experiment
While many bacterial species form spores, partially dehydrated cells surrounded by a tough protective coating, their remarkable ability makes them pose a threat in the form of bacterial anthrax, as well as a contamination hazard in medicine and the food industry.
The researchers decided to test whether dormant spores of Bacillus subtilis (an aerobic organism commonly found in soil) could detect short-lived environmental signals that were not strong enough to trigger a return to life. They found that the spores could identify such small inputs and if the sum reached a certain threshold, they decided to come out of the dormant state and resume biological activity, ‘resurrect’.
Thus, the model suggests that dormant bacterial spores use electrochemical energy stored in their bodies in the form of potassium ions to break down external conditions. Without being metabolically active, the spores release stored potassium ions to detect different environmental stimuli. When the sum total of all potassium ions released over time in response to various external stimuli crosses the threshold value, the spores become activated.
“The way the spores process information is similar to how the neurons in our brain operate ,” Süel clarifies. “In both bacteria and neurons, small, brief inputs are summed over time to determine whether a threshold is reached. Upon reaching the threshold, the spores begin their return to life, while the neurons fire an action potential.” to communicate with other neurons.
The researchers believe that this discovery about spores reshapes preconceptions about cells in extremely dormant states that appear dead.
“This work suggests alternative ways of dealing with the potential threat posed by pathogenic spores and has implications for what to expect from extraterrestrial life. If scientists do find life on Mars or Venus, it is likely to be in a dormant state and we now know .” that a life form that appears to be completely inert may still be able to think of its next steps .”
Reference: Kaito Kikuchi, Leticia Galera-Laporta, Colleen Weatherwax, Jamie Y. Lam, Eun Chae Moon, Emmanuel A. Theodorakis, Jordi Garcia-Ojalvo, Gürol M. Süel. Electrochemical potential enables dormant spores to integrate environmental signals. Science, 2022 DOI: 10.1126/science.abl7484
