Zur Kenntnis und kataphoretischen Bestimmung des isoelektrischen Punktes einiger Bakterien

Abstract

It is possible to neutralize the interfering boundary surface charge of the cell membrane by staining with suitable basic dyes,making it possible to determine the isoelectric point (IEP) of micro-organisms without injury by direct cataphoresis. At the same time it is possible to verify of the vitality by the use of the fluorochrome acridin orange. The IEP of living bacteria is considerably above the previously given values. The reason for this is that the methods of detn. formerly used cause serious injury to the protoplasm. The change in the submicroscopic structure of the plasma is expressed in a shift in the IEP. With yeast and bacteria the IEP shifted to lower values with cell death. Different methods of killing give different shifts in the IEP.