EDGERTON GERMESHAUSEN AND GRIER INC SANTA BARBARA CA
Differential light-scattering techniques were investigated as a physical method for the rapid identification of various microorganisms. Results of inverse scattering theory suggest that each microorganism scatters light in an essentially unique pattern. Measurements on nonbiological scatterers confirm the possibility that detailed differential scattered intensity data may be used as an identification fingerprint. Calculations are presented which contrast the expected scattering characteristics of certain microorganisms. Experimental and instrumentation difficulties and possible procedures are discussed. A critical review of immersion refractometry procedures is included, which indicates that conventional procedures may yield erroneous results when applied to small andor inhomogeneous cells. Elementary experiments reported on include a study of the negligible effects of laser radiation on viable cells, some preliminary culturing procedures to produce spore suspensions of Bacillus globisporus and B. sphaericus, and a conventional differential scattering measurement on a monodispersion of 1-micron latex spheres. A future program of experimental confirmation is recommended. The mathematical formulations of light scattering from spherically symmetric objects, Rayleigh-Gans scattering theory, and alignment of ellipsoidal structures in a flowing stream are also summarized.