title: Food availability affects the strength of mutualistic host-microbiota interactions in Daphnia magna.
abstract: The symbiotic gut microbial community is generally known to have a strong impact on the fitness of its host. Nevertheless, it is less clear how the impact of symbiotic interactions on the hosts' fitness varies according to environmental circumstances such as changes in the diet. This study aims to get a better understanding of host-microbiota interactions under different levels of food availability. We conducted experiments with the invertebrate, experimental model organism Daphnia magna and compared growth, survival and reproduction of conventionalized symbiotic Daphnia with germ-free individuals given varying quantities of food. Our experiments revealed that the relative importance of the microbiota for the hosts' fitness varied according to dietary conditions. The presence of the microbiota had strong positive effects on Daphnia when food was sufficient or abundant, but had weaker effects under food limitation. Our results indicate that the microbiota can be a potentially important factor in determining host responses to changes in dietary conditions. Characterization of the host-associated microbiota further showed that Aeromonas sp. was the most prevalent taxon in the digestive tract of Daphnia.
authors.affiliation: Laboratory of Aquatic Biology, Science & Technology, KULeuven Campus Kulak, Kortrijk, Belgium.
authors.forename: Martijn
authors.initials: M
authors.lastname: Callens
authors.affiliation: Laboratory of Aquatic Biology, Science & Technology, KULeuven Campus Kulak, Kortrijk, Belgium.
authors.forename: Emilie
authors.initials: E
authors.lastname: Macke
authors.affiliation: Laboratory of Aquatic Biology, Science & Technology, KULeuven Campus Kulak, Kortrijk, Belgium.
authors.forename: Koenraad
authors.initials: K
authors.lastname: Muylaert
authors.affiliation: Laboratory of Aquaculture & Artemia Reference Center, Department of Animal Production, UGent, Ghent, Belgium.
authors.forename: Peter
authors.initials: P
authors.lastname: Bossier
authors.affiliation: Laboratory for Process Microbial Ecology and Bioinspirational Management, Department of Microbial and Molecular Systems, KULeuven Campus De Nayer, Sint-Katelijne-Waver, Belgium.
authors.forename: Bart
authors.initials: B
authors.lastname: Lievens
authors.affiliation: Laboratory for Process Microbial Ecology and Bioinspirational Management, Department of Microbial and Molecular Systems, KULeuven Campus De Nayer, Sint-Katelijne-Waver, Belgium.
authors.forename: Michael
authors.initials: M
authors.lastname: Waud
authors.affiliation: Laboratory of Aquatic Biology, Science & Technology, KULeuven Campus Kulak, Kortrijk, Belgium.
authors.forename: Ellen
authors.initials: E
authors.lastname: Decaestecker
mesh_terms: D000818:Animals; D049628:Body Size; D003621:Daphnia / Q000254:growth & development* / Q000382:microbiology*; D004032:Diet; D004777:Environment; D041981:Gastrointestinal Tract / Q000382:microbiology*; D054884:Host-Pathogen Interactions; D064307:Microbiota; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012098:Reproduction; D013559:Symbiosis
chemical_list: D012336:RNA, Ribosomal, 16S