Comparison of Quasielastic Light Scattering and Laser Diffractometry as Nondestructive Probes into the Structure of Bacillus sphaericus Spores Produced at Different Temperatures.

Volume 62, no. 5, p. 1702, column 2, equation 3: the equation should read as follows. g(sup1)((tau)) = [g(sup2)((tau)) - 1](sup1/2) = exp[-K(sup2)(D(inf1) cos(sup2)(alpha) + D(inf2) sin(sup2)(alpha))(tau)] (3) [This corrects the article on p. 1699 in vol. 62.].

Comparison of Quasielastic Light Scattering and Laser Diffractometry as 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 directly compared the two with a destructive procedure, namely, scanning electron microscopy (SEM), for quasispherical spores of Bacillus sphaericus. Because of the different physical aspect measured, the sizes derived by QLS and LD are, as could be expected for spores with an exosporium, significantly different. The larger estimates obtained by QLS (1.70, 1.58, and 1.14 (mu)m for spores produced at 15(deg)C [BS15], 20(deg)C [BS20], and 30(deg)C [BS30], respectively) than by LD (0.56 [BS15], 0.58 [BS20], and 0.52 [BS30] (mu)m) and SEM (0.64 [BS15], 0.58 [BS20], and 0.70 [BS30] (mu)m) are explained in terms of the detection by QLS, LD, and SEM of different spore layers and the degree of nonsphericity of the latter.

The application of laser diffractometry to study the water content of spores of Bacillus sphaericus with different heat resistances.

The distribution of water in the protoplast and integument of three populations of Bacillus sphaericus spores was determined by laser diffractometry together with the sizes of their integuments and protoplasts. The spores were produced at 15, 20 and 30 degrees C. Spores grown at 15 degrees C had protoplast and integument water contents similar to those produced at 20 degrees C, while those grown at 30 degrees C had significantly lower water contents than the other two populations. The inner (or protoplast) radii of the spores produced at 15, 20 and 30 degrees C were 0.41 +/- 0.02 microns, 0.42 +/- 0.01 microns and 0.38 +/- 0.02 microns whilst the outer (or whole spore) radii were 0.56 +/- 0.01 microns, 0.58 +/- 0.01 microns and 0.52 +/- 0.02 microns respectively. The ratios of integument to protoplast radius were 0.40 +/- 0.02, 0.43 +/- 0.07 and 0.41 +/- 0.03 respectively.

Dynamic light-scattering studies on the effect of heat and disinfectants on spores of Bacillus cereus.

The relative stability of spores of Bacillus cereus grown at three different temperatures was examined by using quasi-elastic light scattering (q.l.s.) in conjunction with turbidity and scanning electron microscopy (s.e.m.). Cultures grown at 20, 30 and 40 degrees C (BC20, BC30 and BC40 respectively) were compared in terms of (i) their effective hydrodynamic radius, rH, as determined from q.l.s. and (ii) their gross morphology, as determined from s.e.m. The effects of autoclaving at 121.1 degrees C on both these properties was also examined. We observed (1) that cultures BC20 and BC30 appeared to have similar values for rH, whereas that of BC40 appeared some 50% higher, and (2) BC40 had a correspondingly much lower heat resistance (its structural integrity was lost after about 20 min autoclaving, whereas that of BC20 and BC30 was retained even after 80 min autoclaving). These data were in good agreement with independent measurements of heat-resistance coefficients. Changes in the hydrodynamic radius, polydispersity (both using q.l.s.) and turbidity were monitored with time on addition of the disinfectants sodium hypochlorite and peracetic acid; again BC40 appeared to have a lower resistance.