How do spores come back to life?

Bacterial spores can be dormant for tens of thousands of years. Now, a study involving MELIS-UPF researchers, shows that spores gather energy from their environment to know when it is the right time to “come back to life”.

Bacterial spores are metabolically inactive and use the stored electrochemical energy to resume their vital functions. Image created by Inés Fuentes from images by Unsplash users CDC and Jeremy Perkins.

Lack of nutrients and stress can cause some bacterial species to enter a dormant state that renders them biochemically inactive. Until now, it was unknown how these bacterial spores could integrate environmental cues to recover from their state of dormancy, that can last tens of thousands of years or more. But a recent study from the Department of Medicine and Life Sciences, Pompeu Fabra University (MELIS-UPF) and the University of California shows that spores accumulate electrochemical potentials from the environment as a signal to decide when to wake up.

This work changes the way we think about spores, which until now were considered inert objects
Gürol Süel, University of California

The study was carried out with Bacillus subtilis spores to which environmental signals were applied. These signals were, each on their own, of insufficient intensity to “wake them up”. As Jordi García-Ojalvo, researcher at MELIS-UPF, explains, thanks to a mathematical model they have discovered that “just like neurons, the spores add up over time small and brief signals to determine whether a threshold is reached. And upon reaching it, they initiate their return to life, just as neurons fire an action potential to communicate with other neurons”. Interestingly, spores do this signal integration without requiring metabolic energy, whereas neurons are one of the most energy-consuming cells in our body.

The authors say that understanding how spores come back to life opens up possibilities for finding new methods to fight pathogenic spores such as anthrax. And it could also give us clues about what life is like in the most extreme terrestrial environments or in other planets.

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