Protoplast water content of bacterial spores determined by buoyant density sedimentation.

Protoplast wet densities (1.315 to 1.400 g/ml), determined by buoyant density sedimentation in Metrizamide gradients, were correlated inversely with the protoplast water contents (26.4 to 55.0 g of water/100 g of wet protoplast) of nine diverse types of pure lysozyme-sensitive dormant bacterial spores. The correlation equation provided a precise method for obtaining the protoplast water contents of other spore types with small impure samples and indicated that the average protoplast dry density was 1.460 g/ml.