What happens when microbes get hangry? How do they come back to life after centuries? Can we talk to them, turn them off and on? Here are some new discoveries about how bacteria work.
The Lazarus Effect
Bacteria can survive for years, even centuries, without nutrients, but how they survive is a centuries-long mystery. Now, research from Harvard Medical School, published in April in the journal Science, shows that cellular sensors shield dormant bacterial spores. A single shield can detect the presence of nutrients and help bring the spore back to life when the bacteria are available.
In a statement, researcher Gurol Suel explains that “this shows that cells in deep dormancy have the ability to process information… that spores can release their stored electrochemical potential energy to calculate about their environment without the need for metabolic activity.”
The new findings could inform new strategies to prevent infections and food spoilage, by helping scientists figure out how to prevent bacterial spores from growing.
Hungry and angry?
New research by Adam Rosenthal, assistant professor of microbiology and immunology at the University of North Carolina Health, found that some bacteria release harmful toxins when they are not properly fed.
Rosenthal selected Clostridium perfringens—a rod-shaped bacterium found in the gut of humans and other vertebrates, insects, and soil—and found that the toxin-producing cells lacked important nutrients.
The researchers then exposed the “bad actor” cells to nutrition and saw that the level of toxins in the community decreased, and the number of “bad actors” decreased. Can “feeding” bacteria prevent or treat certain infections in humans and animals? In his study published in April in Nature Microbiology, Rosenthal suggests that this may be the case.
He is now in the process of partnering with colleagues across UNC to apply his findings to the fight against antibiotic tolerance (one step below antibiotic resistance). Such tolerance may result in less effective treatment, but the mechanisms controlling tolerance are not yet well understood.
Talking to germs
Like neurons in the human brain, bacteria use electrical signals to communicate. “Bacterial nanowires” allow bacteria to form networks and coordinate behavior. Now, researchers have discovered a way to potentially control this electrical signal. In a study published in Advanced Science in February, scientists from the University of Warwick and Politecnico di Milano succeeded in changing electrical signals between bacteria using a “photoswitch” – a molecule that binds to the bacteria and changes its structure when exposed to light. In theory, it could be used to control bacterial behavior.
Further research could help harness this discovery and possibly prevent infections, combating antimicrobial resistance. “This approach can be used to construct bacterial hybrids that can sense light and perform useful functions, such as drug delivery to hard-to-reach places in the body,” the report states.
For mouthless, lungless bacteria, “breathing” is complicated. Geobacter, a common groundwater-dwelling genus, ingests organic waste and “exhales” it through thin, conductive filaments, generating a small electrical 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 at Yale University, including Nikhil Malvankar, assistant professor of molecular biophysics and biochemistry, discovered that bacteria can be shut down by removing hair-like structures called pili inside each bacterial cell. Generate an electric current. Conversely, by adding certain chemicals, they were able to stimulate the production of pili and thus the electrical current. This on/off switch, the researchers say, could inspire new technologies, such as powerful microbe-powered batteries that generate electrical energy using microbial cells.
What exactly powers life in the ocean?
A study by researchers from Monash University, Melbourne, published in the journal Nature Microbiology in February, shows that these deep-sea microbes are not the only ones that can survive without sunlight.
Trillions of microbes in ocean regions from the tropics to the poles are able to use chemosynthesis (the metabolism of hydrogen and carbon monoxide) instead of photosynthesis to survive, the report says.
“We found genes capable of consuming hydrogen in eight distant types of microbes known as phyla, and we found that this survival strategy becomes more common the deeper they live,” says microbiologist Rachel Lappan, who led the study.
A previous study by the same researchers focusing on soil bacteria found that there can also be a wide range of survival in atmospheric hydrogen and carbon monoxide.
In the oceans, “we’ve seen hydrogen and carbon monoxide ‘fed’ microbes in everything from urban bays to areas around tropical islands, hundreds of meters below the surface and beneath the ice sheets of Antarctica,” says Professor Chris Greening. University’s Biomedicine Discovery Institute. “Probably the first life emerged in deep-sea vents using hydrogen, not sunlight, as an energy source. It’s incredible that, after 3.7 billion years, so many microbes in the oceans are still using this high-energy gas and we still don’t fully understand it. We have ignored.”