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Damage of Escherichia coli membrane by bactericidal agent polyhexamethylene guanidine hydrochloride: micrographic
1State Key Laboratory of Bioreactor Engineering, School of Biotechnology, East China University of Science and Technology, Shanghai, China.
Aims:
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).
Methods And 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.
Significance And Impact Of The Study:
The presented information helps understand the bactericidal mechanism of PHMG by membrane damage.
Insights
Polyhexamethylene guanidine hydrochloride (PHMG) damages Escherichia coli membranes in a dose-dependent manner. High PHMG concentrations cause significant structural collapse and leakage, leading to bacterial inactivation.
Area of Science:
- Microbiology
- Biochemistry
Background:
- Polyhexamethylene guanidine hydrochloride (PHMG) is a biocide with antimicrobial properties.
- Understanding the precise mechanisms of PHMG's action is crucial for its effective application.
Purpose of the Study:
- To elucidate the micrographic evidence of membrane and intracellular structural damage in Escherichia coli strain 8099 induced by PHMG.
- To investigate the dose-dependent bactericidal effects of PHMG on E. coli.
Main Methods:
- Beta-galactosidase activity assay.
- Fluorescein-5-isothiocyanate confocal laser scanning microscopy.
- Field emission scanning electron microscopy (FESEM).
- Transmission electron microscopy (TEM).
Main Results:
- Low PHMG dose (13 μg/mL) caused slight outer membrane damage and increased cytoplasmic membrane permeability.
- High PHMG dose (23 μg/mL) resulted in outer membrane collapse, pore formation, and severe intracellular damage.
- Intracellular component leakage and subsequent cell inactivation were observed at high PHMG concentrations.
Conclusions:
- Dose-dependent membrane disruption is the primary bactericidal mechanism of PHMG against E. coli.
- High PHMG concentrations likely induce local membrane pore formation.
- This study provides critical micrographic evidence of PHMG-induced cellular damage in E. coli.
