Physical Surface Features and Chemical Density of Dry Bacterial Spores.

Berlin, E. (U.S. Department of Agriculture, Washington, D.C.), H. R. Curran, and M. J. Pallansch. Physical surface features and chemical density of dry bacterial spores. J. Bacteriol. 86:1030-1036. 1963.-Gas-displacement and gas-adsorption techniques were used to determine the chemical density and physical surface properties of the spores of Bacillus subtilis 15U, B. cereus 720, and B. stearothermophilus 1518 held in the dry state. Neither the observed densities nor the specific surface areas measured could be correlated with the heat resistance of the spores studied. Analysis of data obtained from a study of the adsorption of nitrogen by spores held at -195 C led to the postulate that the surface of the dry spore is relatively smooth and impervious, and is characterized by the presence of a few pores having radii of approximately 300 A. The presence of such orifices could account for the permeability of the spore form reported by other workers.