How half-dead bacteria know it’s time to revive

(ORDO NEWS) — Being in a state of spores, covered with a strong shell, bacteria survive adverse conditions, stopping all their life processes.

In fact, such a cell is almost dead, but scientists have found that even “dead” bacteria constantly monitor the state of the external environment, reacting even to minor changes in conditions.

Unlike plants and fungi, bacterial spores do not serve to reproduce: in particular, they are formed inside cells during a sharp deterioration in environmental conditions, for example, a decrease in temperature or a decrease in humidity.

In this state, the bacterium is able to withstand various physical and chemical influences, remaining viable for many years: a case is known when bacterial spores germinated, formed about 30 million years ago.

In order to maintain the ability to germinate for so long, the bacterium nullifies all its physiological processes, stopping even the movement of the cytoplasm due to the loss of most of the water.

But it was not known whether it retained the ability to “track” the state of the external environment, reacting to those conditions that were not yet suitable for germination.

In other words, are bacterial spores inert until the moment of germination, or do they somehow react to minor changes from the outside?

Biologists at the University of California San Diego (USA) were able to unravel this mystery by discovering that spores of hay bacillus ( Bacillus subtilis ) act like capacitors, using stored electrochemical energy to monitor external conditions in a state of complete rest.

Due to this, disputes react even to short-term and weak improvements in external conditions, but germinate only when the sum of such changes reaches a certain threshold suitable for full-fledged life.

After developing a mathematical model to explain this process, the researchers found that spores use membrane potential to track the state of their environment.

Roughly speaking, the spore releases a small amount of potassium ions in response to each slight improvement in external conditions (in this case, these were amino acids added to the solution with spores), but germinates only when the difference in potassium concentrations outside and inside the spore shell reaches the desired value.

This is similar to how the neurons in our brain work, in which the membrane potential is used to transmit signals between cells.

It is amazing that bacteria can release potassium ions without any energy expenditure, and neurons are one of the most “energetic” cells in our body.

The new data allows us to rethink our understanding of bacterial spores and may serve in space missions looking for signs of the existence of extraterrestrial life.

If in the future astronauts find bacterial spores on meteorites or other planets, by monitoring the membrane potential, scientists can determine the optimal conditions for the germination of such organisms and transform them into a full-fledged cell for further study.


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