COMPARISON OF QUASI-ELASTIC LIGHT-SCATTERING AND LASER DIFFRACTOMETRYAS NONDESTRUCTIVE PROBES INTO THE STRUCTURE OF BACILLUS-SPHAERICUS SPORES PRODUCED AT DIFFERENT TEMPERATURES

Quasielastic light scattering (QLS) and laser diffractometry (LD) are relatively novel nondestructive procedures for estimating the sizes of bacterial spores in suspension. This study for the first time directl y compared the two with a destructive procedure, namely, scanning elec tron microscopy (SEM), for quasispherical spores of Bacillus sphaericu s. Because of the different physical aspect measured, the sizes derive d by QLS and LD are, as could be expected for spores with an exosporiu m, significantly different. The larger estimates obtained by QLS (1.70 , 1.58, and 1.14 mu m for spores produced at 15 degrees C [BS15], 20 d egrees C [BS20],and 30 degrees C [BS30], respectively) than by LD (0.5 6 [BS15], 0.58 [BS20], and 0.52 [BS30] mu m) and SEM (0.64 [BS15], 0.5 8 [BS20], and 0.70 [BS30] mu m) are explained in terms of the detectio n by QLS, LD, and SEM of different spore layers and the degree of nons phericity of the latter.