Degradation pathway of homoserine lactone bacterial signal molecules by halogen antimicrobials identified by liquid chromatography with photodiode array and mass spectrometric detection

The degradation pathway of acylated homoserine lactone bacterial signaling molecules by oxidizing hypochlorite and stabilized hypobromite antimicrobials has been characterized. A reversed-phase HPLC separation using a cyano column was developed to detect the parent lactones, lactone-hydrolysis products, and halogenation products. Elucidation of the structures of the reaction products was done with the aid of online photodiode array UV spectroscopy and atmospheric pressure chemical ionization mass spectrometry. Quantitative output of the HPLC method was also used to estimate the kinetics of the degradation pathway. The results of this work found that only β-keto-amide signal molecules are halogenated, where normal amide signals are not, and may represent one possible mechanism for control of industrial biofilms.