Indexed on: 02 Jul '16Published on: 02 Jul '16Published in: Environmental Science & Technology
In our previous study, we reported that the transport of monochloramine is affected by the extracellular polymeric substance (EPS) composition, which in turn affected the cell viability of both biofilm and detached clusters (DOI: 10.1021/es405353h). However, while the transport and reaction of monochloramine in biofilm could be observed, the specific biomolecules reacting with the disinfectant and the mechanism of disinfection remained elusive. In this study, the impact of EPS composition on bacteria disinfection by monochloramine was qualitatively determined using both wild-type and isogenic mutant Pseudomonas strains with different EPS secretion capacity and composition. In order to evaluate their EPS reactivity and contribution to susceptibility to monochloramine, the bacteria disinfection process was investigated using Fourier Transform Infrared Spectroscopy and Matrix-Assisted Laser Desorption/Ionization Time-of-Flight/Time-of-Flight Mass Spectrometry. Canonical correlation analysis and partial least square regression modeling were employed to explore the changes that EPS underwent during the monochloramine disinfection process. The analyses results suggested significant reactions of the monochloramine with peptide fragments of proteins that are associated with carbohydrate utilization. Selected enzymes also showed different levels of inhibition by monochloramine when tested.