Accession Number : AD0803226

Title :   OSMOTIC RESPONSES AND LIGHT SCATTERING OF BACTERIA,

Corporate Author : FORT DETRICK FREDERICK MD

Personal Author(s) : Bateman, John B.

Report Date : OCT 1966

Pagination or Media Count : 43

Abstract : Passive osmotic modification of washed bacterial cells involves changes of cell volume and composition. Expressed in terms of an appropriately simplified cell model, these changes correspond to changes in the size parameter and relative refractive index of the equivalent homogeneous sphere. Calculating these changes, in conjunction with available data from the theory of light scattering, allows prediction of the direction and magnitude of osmotically induced changes of light scattering of bacterial suspensions. In this study we measured changes in the two principal plane-polarized components of the light scattered at 90 degrees by suspensions of washed Serratia marcescens illuminated with unpolarized monochromatic light. The results are compatible with those predicted only when supplemented by the assumption of heterodispersity of effective particle diameter in the suspension. Then, and within the limitations imposed by uncertainties in values of cell volume change and by lack of detailed knowledge of the nature of the osmotic response, the data suggest that the Mie theory can be used to interpret changes of light scattering in suspensions of markedly nonspherical, nonuniform, and probably anisotropic cells. To detect departures from theoretical behavior, it is useful to illuminate the suspensions with light polarized in, and perpendicular to, the plane of observation, and to examine the scattered light through an analyzing nicol crossed with respect to the polarizer. For S. marcescens these two components of the 90-degree scattered intensity are small but significant. (Author)

Descriptors :   (*BACTERIA, PHYSICAL PROPERTIES), OPTICAL PROPERTIES, LIGHT, SCATTERING, REFRACTIVE INDEX, OSMOSIS, SOLUTIONS(MIXTURES), SERRATIA MARCESCENS, SPHERES, POLARIZATION, POLAROGRAPHIC ANALYSIS.

Subject Categories : Microbiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE