Determination of conductivity of bacteria by using cross-flow filtration.

An important property of the bacterial surface is its conductivity. To obtain reliable conductivity values, it is essential to handle the cells as gently as possible during the measurement procedure. We have developed a method where a standard conductivity meter is used in combination with cross-flow filtration, thus avoiding repeated centrifugation and resuspension. With this method, the conductivity of Bacillus subtilis was determined to be 7,000 microS/cm, which is a deviation from previously published data by almost an order of a magnitude.