REFRACTION AND ABSORPTION OF LIGHT IN BACTERIAL SUSPENSIONS,
Abstract
The apparent average refractive indices of three types of microorganism in liquid suspension have been estimated by two methods. In the first, the refractive index of the aqueous suspension is measured in an interferometer, the bacterial cell volume fraction is estimated from the dilution of an added inert solute, and the refractive index of the disperse phase is calculated with the aid of a mixture rule. In the second method, optical density spectra of suspensions in several concentrated solutions of nonpenetrating solutes are measured as a function of the refractive index, n1, of the solution. The value of n1 when the optical density, E, has its smallest value is equated to the average cell refractive index and the constants of the parabola E(n1) are related to the heterogeneity of the cell population in respect to refractive index. The preliminary results obtained by the two methods are in satisfactory agreement and are consistent with the specific refractive increments of protein and nucleic acid and their concentrations in the cell. It is pointed out that measurements of optical density spectra can also give useful information concerning the number and size of cells in a suspension and their optical dispersion constants. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1965
- Accession Number
- AD0465196
Entities
People
- Edwin L. Carstensen
- Jack Wagman
- John B. Bateman
Organizations
- United States Army Biological Warfare Laboratories