Combining electroporation with antimicrobials allows to achieve higher bacterial inactivation than if only one method is used. Our purpose was to determine the effect of antibiotic’s mode of action on its potentiation by electroporation and the effect of gram-positive and gram-negative bacteria cell wall structure. To gain an improved understanding of the mechanisms underlying this potentiation, we established a more systematic approach, which enabled us to separate the influence of individual parameters. Highest potentiation by electroporation was achieved for antibiotics that require transport across the cell wall envelopes to reach their target. For Escherichia coli bacteria, this was ampicillin, which only has to pass through the outer membrane, and for Lactiplantibacillus plantarum bacteria, this was tetracycline, which has to pass across the entire cell wall. To a lesser extent, potentiation by electroporation was also achieved for antibiotics that do not require transport across the cell envelopes, which means that in addition to increased antibiotic transport, membrane damage and leakage of cell contents are also important. We also determined the influence of electric pulses on the structure of plasmid and genomic DNA. Exposing the plasmid DNA to electric pulses mainly caused unwinding from an additionally coiled covalently closed circle to an open circle shape, the proportion of these changes depended on the delivered energy. Exposing the genomic DNA to electric pulses led to its fragmentation, however, the proportion of these changes did not depend on the electroporation parameters or the delivered energy.
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