A natural odor attraction between lactic acid bacteria and the nematode Caenorhabditis elegans

ISME J. 2016 Mar;10(3):558-67. doi: 10.1038/ismej.2015.134. Epub 2015 Aug 4.

Abstract

Animal predators can track prey using their keen sense of smell. The bacteriovorous nematode Caenorhabditis elegans employs sensitive olfactory sensory neurons that express vertebrate-like odor receptors to locate bacteria. C. elegans displays odor-related behaviors such as attraction, aversion and adaptation, but the ecological significance of these behaviors is not known. Using a combination of food microbiology and genetics, we elucidate a possible predator-prey relationship between C. elegans and lactic acid bacteria (LAB) in rotting citrus fruit. LAB produces the volatile odor diacetyl as an oxidized by-product of fermentation in the presence of citrate. We show that C. elegans is attracted to LAB when grown on citrate media or Citrus medica L, commonly known as yuzu, a citrus fruit native to East Asia, and this attraction is mediated by the diacetyl odor receptor, ODR-10. We isolated a wild LAB strain and a wild C. elegans-related nematode from rotten yuzu, and demonstrate that the wild nematode was attracted to the diacetyl produced by LAB. These results not only identify an ecological function for a C. elegans olfactory behavior, but contribute to the growing understanding of ecological relationships between the microbial and metazoan worlds.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacteria / metabolism*
  • Caenorhabditis elegans / physiology*
  • Caenorhabditis elegans Proteins / metabolism
  • Chemotaxis*
  • Lactic Acid / analysis
  • Lactic Acid / metabolism*
  • Odorants / analysis
  • Olfactory Receptor Neurons / metabolism

Substances

  • Caenorhabditis elegans Proteins
  • Lactic Acid