Pietschke, CleoTreitz, ChristianForet, SylvainSchultze, AnnikaKunzel, SvenTholey, AndreasBosch, Thomas C.G.Fraune, Sebastian2021-07-020027-8424http://hdl.handle.net/1885/238525Bacterial communities colonize epithelial surfaces of most animals. Several factors, including the innate immune system, mucus composition, and diet, have been identified as determinants of host-associated bacterial communities. Here we show that the early branching metazoan Hydra is able to modify bacterial quorum-sensing signals. We identified a eukaryotic mechanism that enables Hydra to specifically modify long-chain 3-oxo-homoserine lactones into their 3-hydroxy-HSL counterparts. Expression data revealed that Hydra's main bacterial colonizer, Curvibacter sp., responds differentially to N-(3-hydroxydodecanoyl)-l-homoserine lactone (3OHC12-HSL) and N-(3-oxododecanoyl)-l-homoserine lactone (3OC12-HSL). Investigating the impacts of the different N-acyl-HSLs on host colonization elucidated that 3OHC12-HSL allows and 3OC12-HSL represses host colonization of Curvibacter sp. These results show that an animal manipulates bacterial quorum-sensing signals and that this modification leads to a phenotypic switch in the bacterial colonizers. This mechanism may enable the host to manipulate the gene expression and thereby the behavior of its bacterial colonizers.This study was supported by DFG Grants FR 3041/2-1 (to S. Fraune) and BO 848/17-2 (to T.C.G.B.) and by Cluster of Excellence “Inflammation at Interfaces” Grant CL-X (to A.T.).application/pdfen-AU© 2017 The AuthorsHydraquorum quenchingquorum sensinginterferencehost–microbe interaction201710.1073/pnas.17068791142020-11-23