Electrical dipole moments of E. Coli in suspensions in water and in water + alcohol mixtures by electric field light scattering

Abstract

Measurements of the electrically induced changes in the intensity of light scattered by particles in suspension permit the determination of the size and electrical parameters of the particles. It has been observed that whereas the addition of alcohols to aqueous polydisperse suspensions of bacterium E. coli results in a slight change in particle size, much more dramatic changes occur in the apparent dipole moments of the micro-organisms. The results are discussed in terms of both the bactericidal action of alcohols and the current physical models for the electrical properties of colloidal particles in suspension. The results are taken to favour interfacial origins for the dipole moments. The possibility of using electro-optic methods for monitoring the interaction of surface active substances with bacteria is briefly mentioned.