Electroeradication of Escherichia Coli is Under the Control of the Conductance of the Pulsing Buffer

摘要

Bacterial viability can be affected by pulsed electric fields (PEFs) offering a new approach for decontamination of liquids for the food industry and for waste water treatment. The molecular mechanisms remain poorly elucidated. One question is the control by the pulsing solution and the role of its conductance. Escherichia coli (E. coli) was chosen as a model system. The strain E. coli BL21(DE3) was grown to its stationary growth phase, washed and re-suspended in a saline solution at a well-controlled conductivity. Survival was evaluated by plating after a proper dilution. Accumulation of microsecond pulses were efficient for electro-eradication as previously reported but, in most cases a capacitive discharge pulse generator was used where the pulse duration might be affected by the buffer composition and undergo changes during the pulse. This was not the case with our approach using a square wave electropulsator. The main conclusion was that eradication was more efficient in a buffer with a significant conductivity. A tentative explanation taking into account the different physical properties of a bacteria is provided.