Editing Quorum sensing (section)

===Modifications===
As mentioned before, N-acyl-homoserine lactones (AHL) are the quorum sensing signaling molecules of the [[gram-negative bacteria]]. However, these molecules may have different functional groups on their acyl chain, and also a different length of acyl chain. Therefore, there exist many different AHL signaling molecules, for example, 3-oxododecanoyl-L-homoserine lactone (3OC12-HSL) or 3-hydroxydodecanoyl-L-homoserine lactone (3OHC12-HSL). The modification of those quorum sensing (QS) signaling molecules is another sort of quorum quenching. This can be carried out by an [[oxidoreductase]] activity.<ref name=":3" /> As an example, we will discuss the interaction between a host, ''[[Hydra vulgaris]]'', and the main colonizer of its epithelial cell surfaces, ''[[Curvibacter]]'' spp. Those bacteria produce 3-oxo-HSL quorum sensing molecules.<ref name=":3" /> However, the oxidoreductase activity of the polyp ''Hydra'' is able to modify the 3-oxo-HSL into their 3-hydroxy-HSL counterparts.<ref name=":3" /> We can characterize this as quorum quenching since there is an interference with quorum sensing molecules. In this case, the outcomes differ from simple QS inactivation: the host modification results in a phenotypic switch of ''Curvibacter'', which modifies its ability to colonize the epithelial cell surfaces of ''H. vulgaris''.<ref name=":3" />