title: Damage of Escherichia coli membrane by bactericidal agent polyhexamethylene guanidine hydrochloride: micrographic evidences.
abstract: OBJECTIVE
  The purpose of this study was to provide micrographic evidences for the damaged membrane structure and intracellular structure change of Escherichia coli strain 8099, induced by polyhexamethylene guanidine hydrochloride (PHMG).
  
  
  RESULTS
  The bactericidal effect of PHMG on E. coli was investigated based on beta-galactosidase activity assay, fluorescein-5-isothiocyanate confocal laser scanning microscopy, field emission scanning electron microscopy and transmission electron microscopy. The results revealed that a low dose (13 microg ml(-1)) of PHMG slightly damaged the outer membrane structure of the treated bacteria and increased the permeability of the cytoplasmic membrane, while no significant damage was observed to the morphological structure of the cells. A high dose (23 microg ml(-1)) of PHMG collapsed the outer membrane structure, led to the formation of a local membrane pore across the membrane and badly damaged the internal structure of the cells. Subsequently, intracellular components were leaked followed by cell inactivation.
  
  
  CONCLUSIONS
  Dose-dependent membrane disruption was the main bactericidal mechanism of PHMG. The formation of the local membrane pores was probable after exposure to a high dose (23 microg ml(-1)) of PHMG. Micrographic evidences were provided about the damaged membrane structure and intracellular structure change of E. coli.
  
  
  CONCLUSIONS
  The presented information helps understand the bactericidal mechanism of PHMG by membrane damage.
authors.affiliation:  State Key Laboratory of Bioreactor Engineering, School of Biotechnology, East China University of Science and Technology, Shanghai, China.
authors.forename: Z X
authors.initials: ZX
authors.lastname: Zhou
authors.affiliation:  Key Laboratory for Ultrafine Materials, Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai, China.
authors.forename: D F
authors.initials: DF
authors.lastname: Wei
authors.affiliation:  Key Laboratory for Ultrafine Materials, Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Guan
authors.affiliation:  Key Laboratory for Ultrafine Materials, Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai, China.
authors.forename: A N
authors.initials: AN
authors.lastname: Zheng
authors.affiliation:  State Key Laboratory of Bioreactor Engineering, School of Biotechnology, East China University of Science and Technology, Shanghai, China.| Key Laboratory of Microbial Metabolism, Ministry of Education, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: J J
authors.initials: JJ
authors.lastname: Zhong
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000648:ultrastructure*; D002463:Cell Membrane Permeability / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000187:drug effects* / Q000648:ultrastructure*; D006146:Guanidines / Q000494:pharmacology*; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D006146:Guanidines; C060540:polyhexamethyleneguanidine; D001616:beta-Galactosidase