Study On The Damage Mechanism Of High Voltage Electric Field To Escherichia Coli K12

This study explores the changes about the Escherichia coli(E.coli)K12 W3110 which treated by high voltage electrostatic field(HVEF)to reveal the damage mechanism about HVEF on E.coli.It includes the change of cell membrane,intracellular enzyme activity,the primary structure and secondary structure of intracellular proteins and reversible repair.The experimental results show:(1)It was oscillatory change with increase of treatment time by determinate the content of nucleic acid and protein in the bacterial eluate after HVEF treatment.These results indicate that HVEF has a damage effect on cell membrane.Flow cytometry was used to analyze the E.coli after HVEF treatment,it was found that the ratio of damaged cell was increased with the increase of processing time at certain electric field strength;when the treatment dose is 5kV*6min and 7kV*6min respectively,the ratio of damaged cell was all maximum,which was(65.13±2.62)%and(45.87±0.45)%.And then the ratio was decreased with the increase of processing time,it meant the damaged cell became the dead cell,showing the cumulative effects of HVEF.(2)To explore the intracellular protein structure of E.coli,there were no differences in the electrophoretic bands of E.coli intracellular proteins between different HVEF treated and untreated,so the high voltage electrostatic field has no effects on the E.coli intracellular proteins of primary structure.In addition,it is found that the 1kV/cm HVEF made the transformation of ?-sheet to a-helix of intracellular proteins.But the 3kV/cm,5kV/cm and 7kV/cm HVEF made the transformation of a-helix and ?-sheet to ?-turn random coil,it meant the ordered structures transformed to disordered structures.So 1kV/cm HVEF might activate the activity of intracellular proteins.The 3kV/cm,5kV/cm and 7kV/cm HVEF had the damage effect on the activity of intracellular protein of E.coli,and the maximum dose was 5kV/cm electric field.Flow cytometry was used to analyze the E.coli after HVEF treatment combined CFDA.When the treatment dose was 5kV/cm*2min and 7kV/cm*2min,the ratio of CFDA positive cell was the minimum of the same electric field,it illustrated HVEF could damage E.coli intracellular enzyme.Then,the enzyme activity increased in different degrees with the increase of treatment time,it indicated HVEF could active E.coli intracellular enzyme and the optimal dose was 5kV/cm*4min and 7kV/cm*6min.In a word,the total varying trend of E.coli intracellular enzyme activity was oscillation decrease with the increase of treatment dose,indicating the cumulative effects of HVEF.