Roundworms use smell to detect harmful bacteria, study reveals

Unique defense mechanism against harmful bacteria

Destruction of mitochondria, iron-containing energy-producing organelles, is an important part of the roundworm’s defense strategy. This is because many invading bacteria need iron to survive.

Researchers believe this preventive response has evolved to protect nematodes from deadly pathogens.

Since roundworms need to consume bacteria to survive, it is essential that they differentiate between nutritious and harmful bacteria.

Danger is detected by bacterial metabolites

The roundworm detects threats using volatile metabolites, compounds released by bacteria into the environment.

One such bacteria, Pseudomonas aeruginosait releases a metabolite called acetylpropionyl.

In laboratory tests, roundworms were seen to detect acetylpropionyl through their olfactory nervous system, and when they did, they triggered a mitochondrial stress response in their gut cells.

Role of olfactory neurons in the immune response of roundworms

The study found that roundworms’ olfactory neurons remain alert even in the absence of an odorant, but become inactive when they detect an odorant.

When the researchers artificially silenced these neurons, the worms’ cells continued their preventive immune response, regardless of whether an odorant was present or not.

Neuroscientist Julian Dishart explained, “Novelty is this C. elegans it’s preparing for a pathogen before it meets the pathogen.”

Potential for similar mechanisms in other animals

Dishart also hinted that other immune responses could be triggered by smelling bacterial odors, and the idea that similar mechanisms are present in other animals is still uncharted territory.

He suggested that since olfaction is conserved in animal lineages, “It is entirely possible that olfaction does something similar in mammals as it does in C. elegans.”

Can humans pick it up?

Future research hopes to see if odors can prime the guts of other animals in a similar way.

Neuroscientist Andrew Dillin asks, “Can pathogens emit an odor that we detect, helping us fight infection?”

“We’ve been testing this in mice. If we find that humans can smell pathogens and react to protect themselves, it’s possible to imagine a future where we develop something like a perfume that repels pathogens.”