EFFECT OF ALTERNATING CURRENT ON GROWTH LAG IN ESCHERICHIA COLI B

Abstract

Effect of alternating current (50 Hz) on the growth of E. coli B was examined. Current intensity affected the length of lag time depending on the inoculum size, shaking rate during cultivation and composition of culture medium. If the cell number of inoculum was less than 108 cells/ml, lag time was prolonged with an increase of the current intensity. On increasing the cell number of inoculum, effect of the current on lag time decreased. Apparently, electric current affects the relationship between the length of lag time and inoculum size. Intensified current had a lethal effect on the cells in a small inoculum size during cultivation. On the other hand, the current had little or no effect on the growth rate and extent of the growth once the growth began. The current had greater effect on the cells cultivated at a lower shaking rate. Supplementation of a certain nutrient such as yeast extract into the medium weakened the effect of the current. Composition of the medium might have changed by exposure to the current. In the present examination, a stimulative effect of electric current on the growth was not observed.