Bacteria get hangry, too

Have you ever been so hungry that you become angry? US researchers have discovered that some bacteria cells get hangry, too, releasing harmful toxins into our bodies when deprived of certain nutrients.

The researchers discovered, using a recently developed technology, that genetically identical cells within a bacterial community have different functions, with some members behaving in a more docile way and others producing the toxins that make us feel ill. Their findings, published in the journal Nature Microbiology, are particularly important in understanding how and why bacterial communities defer duties to certain cells — and could lead to new ways to tackle antibiotic tolerance further down the line.

“Bacteria behave much more differently than we traditionally thought,” said lead researcher Adam Rosenthal, an assistant professor at the University of North Carolina (UNC) at Chapel Hill. “Even when we study a community of bacteria that are all genetically identical, they don’t all act the same way. We wanted to find out why.”

Rosenthal decided to take a closer look into why some cells act as ‘well-behaved citizens’ and others as ‘bad actors’ that are tasked with releasing toxins into the environment. He selected Clostridium perfringens — a rod-shaped bacterium that can be found in the intestinal tract of humans and other vertebrates, insects and soil — as his microbe of study.

With the help of a device called a microfluidic droplet generator, the researchers were able to separate, or partition, single bacterial cells into droplets to decode every single cell. They found that the C. perfringens cells that were not producing toxins were well-fed with nutrients; on the other hand, toxin-producing C. perfringens cells appear to be lacking those crucial nutrients.

“If we give more of these nutrients, maybe we can get the toxin-producing cells to behave a little bit better,” Rosenthal said.

The researchers then exposed the bad actor cells to a substance called acetate. Their hypothesis rang true: not only did toxin levels drop across the community, but the number of bad actors reduced as well. But in the aftermath of these results, even more questions are popping up.

Now that he knew that nutrients played a significant role in toxicity, Rosenthal wondered if there were particular factors found in the environment that may be ‘turning on’ toxin production in other types of infections, or if this new finding is only true for C. perfringens. He also theorised that introducing nutrients to bacteria could provide a new alternative treatment for animals and humans alike.

For example, C. perfringens is a powerful foe in the hen house. As the food industry is shifting away from the use of antibiotics, poultry are left defenceless. The recent findings may give farmers a new tool to reduce pathogenic bacteria without the use of antibiotics.

As for humans, Rosenthal is in the process of partnering with colleagues across UNC to apply his recent findings to tackling antibiotic tolerance. In the meantime, he will continue to research these increasingly complex bacterial communities to better understand why they do what they do.

Fluorescent microscope image shows a population of genetically identical cells. The cell in green is expressing a green-fluorescent protein that is expressed by cells that are able to take up DNA from the environment. Image credit: Rosenthal et al.