Factors Affecting the Surviving Fractions of RestingEscherichia coliB and K-12 Cells Exposed to Alternating Current

Resting Escherichia coli B and K-12 cells suspended in a phosphate buffer solution were exposed to alternating current (AC) of 50 Hz. The surviving fractions of cells exposed to AC were decreased with an increase in current density from 0 to 300mA/cm2 at 29±3°C for a definite exposure time. At a definite current density the fractions were decreased proportionally with exposure time. Even for conditions of definite exposure time and current density, the fractions varied depending on the concentration of cells initially suspended in buffer solution in AC-exposure chamber. E. coli cells were more resistant to AC-exposure under anaerobic conditions than aerobic conditions. Addition of catalase to the cell suspension during AC-exposure effectively protected both strains. Methionine and albumin had mild protective effects, but chemicals, such as cysteine, ehanol or α-tocopherol had little protective effect.