Cell Wall Thickness, Size Distribution, Refractive Index Ratio and Dry Weight Content of Living Bacteria (Stapylococcus aureus)

Abstract

I HAVE described¹ experiments on the identification of living bacteria using their differential light scattering signatures, following a theoretical study² which proposed that different biochemical structures should scatter light in essentially different manners. For water suspended bacteria, the Rayleigh–Gans scattering theory² does indeed describe the light scattering measurements to within experimental error³. As a consequence of the excellent correspondence between theory and experiment, I have been able to estimate the average cell wall thickness of ^{Staphylococcus aureus} from light scattering data obtained from living cells suspended in water. Further, I have deduced a rather accurate characterization of the cellular size distribution, as well as a certain refractive index ratio. On the basis of the ratio the dry weight content of the cell wall and cytoplasm can be estimated. Until now there seems to have been no means⁴ by which the ultra-structure of living cells might be measured directly.