Modulation of sensory perception by hydrogen peroxide enables Caenorhabditis elegans to find a niche that provides both food and protection from hydrogen peroxide

Hydrogen peroxide (H(2)O(2)) is the most common chemical threat that organisms face. Here, we show that H(2)O(2) alters the bacterial food preference of Caenorhabditis elegans, enabling the nematodes to find a safe environment with food. H(2)O(2) induces the nematodes to leave food patches of laboratory and microbiome bacteria when those bacterial communities have insufficient H(2)O(2)-degrading capacity. The nematode’s behavior is directed by H(2)O(2)-sensing neurons that promote escape from H(2)O(2) and by bacteria-sensing neurons that promote attraction to bacteria. However, the input for H(2)O(2)-sensing neurons is removed by bacterial H(2)O(2)-degrading enzymes and the bacteria-sensing neurons’ perception of bacteria is prevented by H(2)O(2). The resulting cross-attenuation provides a general mechanism that ensures the nematode’s behavior is faithful to the lethal threat of hydrogen peroxide, increasing the nematode’s chances of finding a niche that provides both food and protection from hydrogen peroxide.