title: Reaction of N-acylhomoserine lactones with hydroxyl radicals: rates, products, and effects on signaling activity.
abstract: Chemical communication in bacteria, sometimes called quorum sensing, is a fundamental microbial process that is based on the exchange of molecular signals between cells. The signaling molecules involved in this process are thermodynamically unstable in some environments and their degradation affects microbial communication. This work reports the oxidation of a series of substituted N-acylhomoserine lactones (AHLs, a class of quorum sensing signals) by hydroxyl radicals. The corresponding bimolecular rate constants were obtained and correlated positively with the length of the acyl side chain (C, in numbers of carbon atoms) ranging from 2.4 × 10(9) M(-1) s(-1) to 9.4 × 10(9) M(-1) s(-1) (C4- to C10-AHL), 2.4 × 10(8) M(-1) s(-1) for 3-oxo C6-AHL, and 2.94 × 10(9) M(-1) s(-1) for 3-oxo C8-AHL. Liquid chromatography-mass spectrometric techniques were applied to qualify the identity and quantify the yields of the hydroxyl radical oxidation products of C6-AHL (aldo, keto, and hydroxylated C6-analogues identified). The biological activity of C6-AHL and associated products was determined using the Vibrio harveyi bioluminescence bioassay. Oxidation resulted in a net increase in assay response indexed against the starting AHL. This result suggested that the application of HO• based technologies such as advanced oxidation processes for biofilm control may result in unintended quorum sensing responses by microbial communities.
authors.affiliation: Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA.
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Frey
authors.forename: Lijian
authors.initials: L
authors.lastname: He
authors.forename: Yiling
authors.initials: Y
authors.lastname: Cui
authors.forename: Alan W
authors.initials: AW
authors.lastname: Decho
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Kawaguchi
authors.forename: P Lee
authors.initials: PL
authors.lastname: Ferguson
authors.forename: John L
authors.initials: JL
authors.lastname: Ferry
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000737:chemistry; D001681:Biological Assay; D002851:Chromatography, High Pressure Liquid; D017665:Hydroxyl Radical / Q000737:chemistry*; D007700:Kinetics; D049449:Luminescence; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D053038:Quorum Sensing; D013050:Spectrometry, Fluorescence; D014733:Vibrio / Q000378:metabolism
chemical_list: C088386:homoserine lactone; D017665:Hydroxyl Radical; D015107:4-Butyrolactone