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

Abstract

Abstract-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.

Energy-efficient biomass processing with pulsed electric fields for bioeconomy and sustainable development

“…The charging time of induced TMV decreases with an increase in the external solution conductivity. The charging (τ m ) time for Escherichia coli was found to be 17–50 μs in a 3 μS/cm (low conductivity) buffer ([ 25 ]. In the 0.2 mS/cm and 1 mS/cm buffers, τ m was considerably reduced and was as short as 1 μs.…”

Cell Membrane Electropermeabilization

“…However, with more classical buffers (0.2 mS/cm and mS/cm), both sm are as short as 1 ms, meaning that the steady state TMP should be reached during the pulse and would be present during a large part of a single pulse duration. 50,51…”