Gut bacteria are tiny but may highly contribute to not only animal's digestive health, but also their overall condition. Some bacteria produce good nutrition, being primary food source for worms, meanwhile others make them sick. The worms avoid those bad or toxic bacteria through smelling. In middle July, Nature published that specific gut bacteria in C. elegans may modify the animal's behavior, influencing food choices. In this study, the researchers grew worms using different bacteria that are known to affect worm perceiving odors. They then tested how the worms reacted to octanol, a large alcohol molecule secreted by some bacteria, which worms normally avoid when it is present at high concentrations.
Dr. O'Donnell and his colleagues found that worms grown on Providencia were less likely to avoid octanol than those grown on other bacteria. Live Providencia bacteria were present in the guts of the worms that moved toward octanol. This suggested that the worms’ behavior could be modified in part by a substance produced by these bacteria.
The study uncovered a pathway involving the chemical tyramine, which is produced by Providencia bacteria in the gut. Tyramine is transformed by the worms’ body into octopamine, which acts as a neurotransmitter. Octopamine targets a receptor on sensory neurons that controls the worms’ aversion to scents. This made the worms more tolerant of octanol. In addition, the researchers found that the bacteria produced odor compounds related to octanol. These findings show how a neurotransmitter produced by gut bacteria can influence behavior.
1. Michael P. O’Donnell et al., (2020) A neurotransmitter produced by gut bacteria modulates host sensory behavior. Nature. Doi: 10.1038/s41586-020-2395-5
2. Gut bacteria influence behavior in worms. Retrieved July 15, 2020 from https://www.nih.gov/news-events/nih-research-matters/gut-bacteria-influence-behavior-worms