title: A natural odor attraction between lactic acid bacteria and the nematode Caenorhabditis elegans.
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.
authors.affiliation: Division of Biological Science and Technology, College of Science and Technology, Yonsei University, Wonju, Korea.
authors.forename: Jae Im
authors.initials: JI
authors.lastname: Choi
authors.affiliation: Division of Biological Science and Technology, College of Science and Technology, Yonsei University, Wonju, Korea.
authors.forename: Kyoung-Hye
authors.initials: KH
authors.lastname: Yoon
authors.affiliation: Division of Biological Science and Technology, College of Science and Technology, Yonsei University, Wonju, Korea.
authors.forename: Saraswathi
authors.initials: S
authors.lastname: Subbammal Kalichamy
authors.affiliation: Division of Biological Science and Technology, College of Science and Technology, Yonsei University, Wonju, Korea.
authors.forename: Sung-Sik
authors.initials: SS
authors.lastname: Yoon
authors.affiliation: Division of Biological Science and Technology, College of Science and Technology, Yonsei University, Wonju, Korea.
authors.forename: Jin
authors.initials: J
authors.lastname: Il Lee
mesh_terms: D000818:Animals; D001419:Bacteria / Q000378:metabolism*; D017173:Caenorhabditis elegans / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism; D002633:Chemotaxis; D019344:Lactic Acid / Q000032:analysis / Q000378:metabolism*; D009812:Odorants / Q000032:analysis; D018034:Olfactory Receptor Neurons / Q000378:metabolism
chemical_list: D029742:Caenorhabditis elegans Proteins; D019344:Lactic Acid