Electric Alarm Clock For Dormant Spores: Inactive Bacteria Integrate Stimuli and Create Bodily Signals

Bacteria have a special ability to survive difficult situations by creating a protective outer layer around their DNA and entering a dormant state. However, when conditions become favorable again, these dormant bacteria, known as spores, can resume their normal activities. However, the process of waking up from dormancy can be risky and if not done correctly, the spore may not survive. The question is, how do spores determine when it is safe to come out of dormancy and resume their normal functions?

Bacillus subtilis spores can determine when it is safe to come out of dormancy by keeping track of how often they encounter nutrients. This allows them to determine when it is the right time to resume normal functions, a process known as germination. Following a recent study analysis published in Science, this ability to count nutrients is key to the survival of these spores.

Waking From Dormancy

According to Gürol Süel, a microbiologist at the University of California, San Diego, spores of the bacterium Bacillus subtilis appear to have almost no detectable biological activity while dormant. However, it is known that the cores of these spores contain positively charged potassium atoms. As these atoms can move freely within the cell without the need for energy, the research team suspected that potassium might play a role in the process of waking the spores up from dormancy, as reported by Scientific American.

To investigate the role of potassium in spore germination, the research team exposed Bacillus subtilis spores to nutrients and used dyes to track the movement of potassium within the spores. They found that, with each exposure to nutrients, more potassium was released from the core of the spore, causing the electrical charge of the core to become more negative. When the electrical charge of the core became negative enough, germination was triggered, similar to how a champagne cork is released when enough pressure is applied.

The number of exposures required to trigger germination varied among the spores, similar to how some champagne corks require more or less twisting to release. In their experiments, the team also found that spores whose potassium movement was impaired showed limited changes in their electrical charge and were less likely to germinate, regardless of how many exposures to nutrients they received.

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Researchers used colorful dyes to illuminate the electrical charges of Bacillus subtilis spores, as seen here, to track how the bacteria responded to pulses of nutrients. Bacteria like these become dormant to survive tough environments, but it wasn’t previously known how they sense when to wake up.

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Electrical Charge Significance

Science News reported that the changes in the electrical charge of a cell can have important effects on the behavior and function of cells in a variety of organisms, including in the brain and plants such as Venus flytraps. The discovery that spores also use changes in electrical charge to trigger germination is exciting because it suggests that this is a widespread process that is not limited to just one type of organism or system. This finding highlights the importance of electrical charge in biology and the potential for similar processes to occur across different fields and boundaries.

Spores are of scientific interest not only because of their unique biology but also due to their practical applications. Some types of spores can cause serious health problems, such as food poisoning or anthrax, and are resistant to most antibiotics. Understanding the process of germination could potentially lead to new ways to kill these spores since they can be revived and then destroyed. Peter Setlow, a biochemist at UConn Health in Farmington who was not involved in the study, noted the potential dangers of certain spores.

There are still many unknown aspects of the process of spore germination, including whether spores can reset their potassium count. Kaito Kikuchi, a biologist at Reveal Biosciences in San Diego who researched while at the University of California, San Diego, noted that we are just starting to understand this process, which is often referred to as a "black box." However, the discovery that spores can track their environment while in a dormant state is an important first step in understanding how they can germinate.