title: Systematic approach to in-depth understanding of photoelectrocatalytic bacterial inactivation mechanisms by tracking the decomposed building blocks.
abstract: A systematic approach was developed to understand, in-depth, the mechanisms involved during the inactivation of bacterial cells using photoelectrocatalytic (PEC) processes with Escherichia coli K-12 as the model microorganism. The bacterial cells were found to be inactivated and decomposed primarily due to attack from photogenerated H2O2. Extracellular reactive oxygen species (ROSs), such as H2O2, may penetrate into the bacterial cell and cause dramatically elevated intracellular ROSs levels, which would overwhelm the antioxidative capacity of bacterial protective enzymes such as superoxide dismutase and catalase. The activities of these two enzymes were found to decrease due to the ROSs attacks during PEC inactivation. Bacterial cell wall damage was then observed, including loss of cell membrane integrity and increased permeability, followed by the decomposition of cell envelope (demonstrated by scanning electronic microscope images). One of the bacterial building blocks, protein, was found to be oxidatively damaged due to the ROSs attacks, as well. Leakage of cytoplasm and biomolecules (bacterial building blocks such as proteins and nucleic acids) were evident during prolonged PEC inactivation process. The leaked cytoplasmic substances and cell debris could be further degraded and, ultimately, mineralized with prolonged PEC treatment.
authors: The State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences , Guangzhou 510640, China.
authors: Hongwei
authors: H
authors: Sun
authors: Guiying
authors: G
authors: Li
authors: Xin
authors: X
authors: Nie
authors: Huixian
authors: H
authors: Shi
authors: Po-Keung
authors: PK
authors: Wong
authors: Huijun
authors: H
authors: Zhao
authors: Taicheng
authors: T
authors: An
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D002374:Catalase / Q000378:metabolism; D002384:Catalysis; D004203:Disinfection; D055664:Electrochemical Techniques; D048168:Escherichia coli K12 / Q000201:enzymology / Q000378:metabolism / Q000528:radiation effects*; D050296:Microbial Viability / Q000528:radiation effects; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000528:radiation effects; D055668:Photochemical Processes; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism; D014025:Titanium / Q000737:chemistry; D014466:Ultraviolet Rays; D014871:Water Microbiology
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; C009495:titanium dioxide; D014025:Titanium; D002374:Catalase; D013482:Superoxide Dismutase