Science: Deeply dormant spores can use stored electrochemical energy to assess their surroundings

In a new study, researchers have found that spores have an extraordinary ability to
assess their surroundings while remaining physiologically dead.
They found that the spores used stored electrochemical energy, like a capacitor, to determine whether conditions were suitable for a return to normal functional life
.

Faced with starvation and stressful conditions, some bacteria enter a dormant state
where life processes stop.
These bacterial cells, called spores, enter a deeply dormant state and are able to withstand extreme heat, pressure, and even the harsh environment
of outer space.
Eventually, when conditions become favorable, spores that may have been dormant for years can wake up in minutes and come back to life
.

The spores wake up
by rehydrating and restarting their metabolism and physiology.
But until now, scientists didn't know if spores were able to monitor their environment "dormantly" without being awakened
.
In particular, it is not known how the spores deal with vague environmental signals
that do not clearly indicate favorable conditions.
Do the spores ignore such mixing conditions or will they notice?

In a new study, researchers from the University of California, San Diego have solved the mystery
.
They found that the spores had an extraordinary ability to
assess their surroundings while remaining physiologically dead.
They found that the spores used stored electrochemical energy, like a capacitor, to determine whether conditions were suitable for a return to normal functional life
.
The results of the study were published in the October 7, 2022 issue of the journal Science in the paper "Electrochemical potential enables dormant spores to integrate environmental signals"
.

Gürol Süel, corresponding author and professor in the Department of Molecular Biology at the University of California, San Diego, said: "This new study has changed the way we think about spores, which were once thought to be inert objects
.
We found that deeply dormant bacterial cells have the ability to process information
.
We found that spores can release their stored electrochemical potential energy to perform calculations about their environment without the need for metabolic activity
.
”

Many bacterial species form spores --- partially dehydrated bacterial cells surrounded by elastic protective layers --- as a survival strategy that allows them to remain dormant for
thousands of years.
This extraordinary ability makes bacterial anthrax a threat and exposes the medical and food industries to contamination risks
.

Süel and his colleagues tested whether dormant Bacillus subtilis spores were able to sense transient environmental signals that were not strong enough to trigger the restoration
of life.
They found that the spores were able to calculate these small signal inputs, and if the sum of the incoming signals reached a certain threshold, they would decide to exit dormancy and resume biological activity
.

The authors developed a mathematical model to help explain this process, finding that the spores use a mechanism called "integration-emission," which evaluates its surroundings based on the flux of potassium ions
.
They found that even if it was brief enough to trigger a favorable signal to leave dormancy, the spores responded
.
Instead of being awakened, the spores respond to each small input signal, releasing some of their stored potassium, and then adding up successive favorable signals to determine if conditions are suitable for exiting sleep
.
This cumulative signal processing strategy can reveal whether external conditions are indeed favorable and prevent spores from "acting prematurely" into the world of
adverse conditions.

"The way spores process information is similar to how neurons in our
brains work," Süel said.
In bacteria and neurons, small, short input signals are added up over time to determine whether a threshold has
been reached.
After reaching the threshold, the spores begin to regain life, while neurons emit an action potential to communicate
with other neurons.
"Interestingly, spores can do this signal integration without the need for any metabolic energy, and neurons are among
the most energy-dependent cells in our body.
"

The authors argue that the new information about the spores reconstructs the popular idea
that bacterial cells are in an extremely dormant state that appears to have died.
Such discoveries have implications
for assessing life on objects such as meteors and for space missions seeking evidence of life.

Süel said, "This new study suggests alternative ways to deal with the potential threat posed by pathogen spores and has implications
for what is expected from extraterrestrial life.
" If scientists had found life on Mars or Venus, it would likely have gone dormant, and we now know that a seemingly completely inert life form might still have the ability to think about its next step
.
(Bio Valley Bioon.
com)

Resources:

1.
Kaito Kikuchi et al.
 Electrochemical potential enables dormant spores to integrate environmental signals.
Science, 2022, doi:10.
1126/science.
abl7484.

2.
The thinking undead: How dormant bacteria calculate their return to life

https://phys.
org/news/2022-10-undead-dormant-bacteria-life.
html