The High-Resolution Architecture and Structural Dynamics of Bacillus Spores

Abstract

The capability to image single microbial cell surfaces at nanometer scale under native conditions would profoundly impact mechanistic and structural studies of pathogenesis, immunobiology, environmental resistance, and biotransformation. Here, using in vitro atomic force microscopy, we have directly visualized high-resolution native structures of bacterial endospores, including the exosporium and spore coats of four Bacillus species in air and water environments. Our results demonstrate that the mechanisms of spore coat self-assembly are similar to those described for inorganic and macromolecular crystallization. The dimensions of individual Bacillus atrophaeus spores decrease reversibly by 12% in response to a change in the environment from fully hydrated to air-dried state, establishing that the dormant spore is a dynamic physical structure. The interspecies distributions of spore length and width were determined for four species of Bacillus spores in water and air environments. The dimensions of individual spores differ significantly depending upon species, growth regimes, and environmental conditions. These findings may be useful in the reconstruction of environmental and physiological conditions during spore formation and for modeling the inhalation and dispersal of spores. This study provides a direct insight into molecular architecture and structural variability of bacterial endospores as a function of spatial and developmental organizational scales.

Performance of Conventional and Antimicrobial-Treated Filtering Facepiece Respirators Challenged with Biological Aerosols

“…(10,13) Its average aerodynamic diameter has been reported to be approximately 1.0-1.2 µm with a fairly broad size distribution (0.5-1.5 µm) that may evolve over time, possibly due to experimental and biological variability. (14) Spores are approximately 0.7 µm in diameter and 1.8 µm in length in the dried state, (15) with an average aerodynamic diameter reported to range from approximately 0.8-1.1 µm. (14,16,17) B. atrophaeus endospores (ATCC #9372) were obtained from Raven Labs (Omaha, Neb.)…”

<i>Bacillus pumilus</i>: Possible Model for the Bioweapon <i>Bacillus anthracis</i>

“…An explanation for this variation may be the amount of water remaining in the spore during preparation [20,21]. Additionally, the method used to determine spore dimensions would impact measurements.…”

“…Scanning electron microscopy has been used [23, this study] and Carrera [11] used transmission electron microscopy. The measurements made by Plomp [21], resulting in the largest reported spore sizes, were based on atomic force microscopy. Spore dimensions for B. atrophaeus in this study (1.31 × 0.75 μm) are in agreement with other reports [11,22] (1.22 × 0.65 μm and 1.21 × 0.68 μm, respectively).…”

Lab-Scale production of Bacillus atrophaeus' spores by solid state fermentation in fifferent types of bioreactors

“…The spores obtained from SSF showed growth characteristics as biofilm formation. Nagel et al (2002) cited by Plomp et al (2005) stated that: "Although very little is known about the mechanistic basis of differences observed is well known that gene expression in SSF may be different from that in other kind of fermentation". A new category of SSF was proposed by Gutierrez-Correa and Villena (2003): fermentation by the accession to the surface or fermented by biofilm.…”