Gut Bacteria May Modify Behavior in Worms, Influencing Eating Habits

Gut bacteria are tiny but may play an outsized role not only in the host animal’s digestive health, but in the animal’s overall well-being. According to a new study in Nature, specific gut bacteria in the worm may modify the animal’s behavior, directing its eating decisions. The research was funded in part by NIH.

“We keep finding surprising roles for gut bacteria that go beyond the stomach,” said Dr. Robert Riddle,  program director at NINDS, which supported the study. “Here, the gut bacteria are influencing how the animal senses its environment and causing it to move toward an external source of the same bacteria. The gut bacteria are literally making their species tastier to the animal.”

Researchers at Brandeis University, led by Dr. Michael O’Donnell, postdoctoral fellow and first author of the paper, and Dr. Piali Sengupta, professor of biology and senior author of the study, were interested in seeing whether it was possible for gut bacteria to control a host animal’s behavior. The group investigated the effects of gut bacteria on how worms, called C. elegans, sniff out and choose their next meal.

Bacteria are the worms’ primary food. In this study, the researchers measured how worms fed different strains of bacteria reacted to octanol, a large alcohol molecule secreted by some bacteria, which worms normally avoid when it is present at high concentrations.

O’Donnell and colleagues discovered that worms grown on Providencia alcalifaciens (JUb39) were less likely to avoid octanol compared to animals grown on other bacteria. Curiously, they found that live JUb39 bacteria were present in the gut of the worms that moved toward octanol, suggesting that the behavior may be determined in part by a substance produced by these bacteria.  

Next, the researchers wanted to know how the bacteria exerted control over the worms.

“We were able to connect the dots, all the way from microbe to behavior, and determine the entire pathway that could be involved in this process,” said O’Donnell.