Biosynthetic requirements for the repair of sublethal membrane damage in Escherichia coli cells after pulsed electric fields.
OBJECTIVE
The aim was to evaluate the biosynthetic requirements for the repair of sublethal membrane damages in Escherichia coli cells after exposure to pulsed electric fields (PEF).


RESULTS
The partial loss of the barrier and homeostatic functions of the cytoplasmic membrane was examined by adding sodium chloride to the recovery media. More than 4 log10 cycles of survivors were sublethally injured after PEF. Repair of such sublethal membrane damages occurred when survivors to PEF were incubated in peptone water for 2 h. Two different types of sublethally injured cells were detected. Whereas a small proportion (<5%) repaired after PEF in less than 2 min, the repair of the remaining 95% injured cells lasted 2 h and was dependent on biosynthetic requirements. The addition of inhibitors such as chloramphenicol, cerulenin, penicillin G, rifampicin and sodium azide to the liquid repair medium showed that the repair required energy and lipid synthesis, and was not dependent on protein, peptidoglican or RNA synthesis.


CONCLUSIONS
Cell survival after PEF is dependent on the repair of the cytoplasmic membrane. Requirement of lipid synthesis for the repair of sublethally injured cells confirms that the cytoplasmic membrane is a target directly involved in the mechanism of inactivation by PEF.


CONCLUSIONS
Knowledge about the damages inflicted by PEF might help in the design of more efficient treatments.
Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain.
D
D
García
P
P
Mañas
N
N
Gómez
J
J
Raso
R
R
Pagán
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002569:Cerulenin / Q000494:pharmacology; D002701:Chloramphenicol / Q000494:pharmacology; D015169:Colony Count, Microbial / Q000379:methods; D003470:Culture Media; D004560:Electricity / Q000009:adverse effects*; D004734:Energy Metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects / Q000502:physiology*; D050356:Lipid Metabolism; D010400:Penicillin G / Q000494:pharmacology; D012293:Rifampin / Q000494:pharmacology; D019810:Sodium Azide / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D003470:Culture Media; D004791:Enzyme Inhibitors; D002569:Cerulenin; D002701:Chloramphenicol; D019810:Sodium Azide; D010400:Penicillin G; D012293:Rifampin