Chatty, hangry, Lazarus-like: Astonishing new findings on how bacteria work

What happens when microbes get hangry? How exactly do they spring back to life after centuries? Can we talk to them, turn them off and on? Here are some of the newest discoveries about how bacteria work.

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The Lazarus effect

Bacteria can survive for years, even centuries, without nutrients, but how they spring back to life has been a centuries-long mystery. Now , research from the Harvard Medical School, published in April in the journal Science, shows that cellular sensors shield dormant bacterial spores. The same shields can detect the presence of nutrients and help the spore spring back to life when sustenance becomes available.

In a statement, researcher Gürol Süel explains that this “shows(s) that cells in a deeply dormant state have the ability to process information… that spores can release their stored electrochemical potential energy to perform a computation about their environment without the need for metabolic activity.”

The new findings could inform novel strategies to prevent infections and food spoilage, by helping scientists learn how to keep bacterial spores from waking up.

Hungry and angry?

New research by Adam Rosenthal, an assistant professor of microbiology and immunology at the University of North Carolina Health, has found that some bacteria release harmful toxins when not well-fed.

Rosenthal selected Clostridium perfringens — a rod-shaped bacterium that can be found in the intestinal tracts of humans and other vertebrates, insects, and soil — and found that toxin-producing cells appeared to be lacking crucial nutrients.

Researchers then exposed the “bad actor” cells to nutrition and saw toxin levels drop across the community, and the number of “bad actors’’ fall. Could “feeding” bacteria prevent or treat certain types of infection in humans and animals? In his study, published in Nature Microbiology in April, Rosenthal suggests that it could.

He is now in the process of partnering with colleagues across UNC to apply his findings to the task of tackling antibiotic tolerance (a step below antibiotic resistance). Such tolerance can result in less-effective treatment, but the mechanisms controlling tolerance are not yet well-understood.

Talking to the germ

Much like the neurons in the human brain, bacteria use electrical signals to communicate. “Bacterial nanowires” allow bacteria to form networks and coordinate behaviour. Now, researchers have discovered a way to potentially control this electrical signalling. In a study published in Advanced Science in February, scientists at the Universities of Warwick and Politecnico di Milano managed to alter electric signals between bacteria using a “photoswitch” — a molecule that binds to the bacteria and changes its structure when exposed to light. In theory, this could be used to control bacterial behaviour.

Further research could use this finding to help tackle and perhaps prevent infections, fight antimicrobial resistance. “This approach can (also) be exploited to build up bacterial hybrids that can perceive light and perform useful tasks, such as drug delivery in hard-to-reach body locations,” the report states.

The on/off switch

For mouthless, lungless bacteria, “breathing” is complicated. Geobacter, a common groundwater-dwelling genus, swallows organic waste and “exhales” through thin, conductive filaments, generating a tiny electric current in the process.

In 2021 scientists discovered how to turn this “engine” off, and on again. In a study published in the journal Cell, researchers from Yale University, including Nikhil Malvankar, an assistant professor of molecular biophysics and biochemistry, discovered that by removing hair-like structures called pili within each bacterial cell, they could turn off the bacteria’s ability to generate electric current. Conversely, by adding certain chemicals, they were able to stimulate the production of pili and thereby the electric current. This on/off switch, researchers state, could inspire new technologies, such as powerful microbe-powered batteries that generate electrical energy using microbial cells.

What’s really powering life in the ocean?

A study by researchers at Monash University, Melbourne, published in the journal Nature Microbiology in February, suggests that it’s not just microbes in the deep ocean that can live without sunlight.

Trillions of microbes in regions of the ocean ranging from the tropics to the poles are able to use chemosynthesis (metabolising hydrogen and carbon monoxide) rather than photosynthesis in order to survive, the report states.

“We found the genes that enable hydrogen consumption present across eight distantly related types of microbes, known as phyla, and we found that this survival strategy becomes more common the deeper they live,” says microbiologist Rachael Lappan, who led the study.

A previous study by the same researchers focused on soil bacteria and found that, there too, a wide range could survive on hydrogen and carbon monoxide drawn from the atmosphere.

In the oceans, “hydrogen and carbon monoxide ‘fed’ microbes in all regions we looked at, from urban bays to areas around tropical islands, hundreds of metres below the surface, and even beneath Antarctica’s ice shelves,” says professor Chris Greening of the university’s Biomedicine Discovery Institute. “The first life probably emerged in deep-sea vents using hydrogen, not sunlight, as the energy source. It’s incredible that, 3.7 billion years later, so many microbes in the oceans are still using this high-energy gas and we’ve completely overlooked this until now.”