Fine Structure of the
            <i>Bacillus thuringiensis</i>
            Spore

Pankratz, H. Stuart; Scherrer, René

doi:10.1128/aem.32.3.438-440.1976

Cited by 19 publications

(15 citation statements)

References 7 publications

(11 reference statements)

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“…This structure often is termed outer coat but should be termed exosporium (see Discussion). The atypical exosporium of this spore lacked the thick, hairlike nap outside of the basal layer, which is present in the typical exosporium of spores of B. megaterium Mgl9 (4) and of B. cereus, B anthrac-is, and B. thuringiensis (18,20,21,29).…”

Section: Resultsmentioning

confidence: 93%

Resistance, germination, and permeability correlates of Bacillus megaterium spores successively divested of integument layers

Koshikawa¹,

Beaman²,

Pankratz³

et al. 1984

J Bacteriol

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A variant strain that produced spores lacking exosporium was isolated from a culture of Bacillus megaterium QM-B1551. Two additional spore morphotypes were obtained from the parent and variant strains by chemical removal of the complex of coat and outer membrane. Among the four morphotype spores, heat resistance did not correlate with total water content, wet density, refractive index, or dipicolinate or cation content, but did correlate with the volume ratio of protoplast to protoplast plus cortex. The divestment of integument layers exterior to the cortex had little influence on heat resistance. Moreover, the divestment did not change the response of either the parent or the variant spores to various germination-initiating agents, except for making the spores susceptible to germination by lysozyme. The primary permeability barrier to glucose for the intact parent and variant spores was found to be the outer membrane, whereas the barrier for the divested spores was the inner membrane.

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Section: Resultsmentioning

confidence: 93%

Resistance, germination, and permeability correlates of Bacillus megaterium spores successively divested of integument layers

Koshikawa¹,

Beaman²,

Pankratz³

et al. 1984

J Bacteriol

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“…The general structural features of Bacillus spores are similar, although only some spores possess a well‐defined exosporium (Henriques and Moran, 2000). All pathogenic Bacillus species, which include B. anthracis , the opportunistic human pathogen B. cereus , and the insect pathogen B. thuringiensis , produce spores with a prominent, loose‐fitting, balloon‐like exosporium (Gerhardt, 1967; Gerhardt et al ., 1976). These three species are closely related evolutionarily and belong to the so‐called B. cereus group.…”

Section: Discussionmentioning

confidence: 99%

Non‐uniform assembly of the Bacillus anthracis exosporium and a bottle cap model for spore germination and outgrowth

Steichen

Kearney

Turnbough³

2007

Molecular Microbiology

119

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SummarySpores of Bacillus anthracis are enclosed by an exosporium composed of a basal layer and an external hair-like nap. The nap is formed by a collagen-like glycoprotein called BclA, while the basal layer contains many different proteins, one of which is a sporespecific alanine racemase (Alr). In this study, we employed fluorescence microscopy and a fluorescently labelled anti-Alr monoclonal antibody (mAb) to examine the distribution of Alr within the exosporium. Binding of the mAb occurred over approximately three-quarters of the exosporium but not in a cap-like region at one end of the spore, indicating the absence or inaccessibility of Alr in this region. We also determined that the cap-like region, or cap, corresponds to the first part of the exosporium assembled within the mother cell during sporulation and the only part of the exosporium assembled in a DexsY mutant strain of B. anthracis. Our results provide the first direct evidence that exosporium assembly is a non-uniform process and suggest that exosporium formation is discontinuous. Finally, we demonstrated that during spore germination and outgrowth, the outgrowing cell always escapes from its exosporium shell by popping through the cap, suggesting that the cap is designed to facilitate the emergence of the outgrowing cell.

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“…It is a complex mem-brane loosely surrounding the spore. Its presence is species specific (23), but it is commonly found on spores from B. cereus, B. anthracis, and B. thuringiensis (11,12,23). The exosporium from B. cereus (23) contains 52% protein, 20% polysaccharide, 12.5% neutral lipid, and 5.5% phospholipid.…”

Section: Discussionmentioning

confidence: 99%

Bacillus thuringiensis HD-73 Spores Have Surface-Localized Cry1Ac Toxin: Physiological and Pathogenic Consequences

Du¹,

Nickerson²

1996

Appl Environ Microbiol

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Spores from Cry ؉ strains of Bacillus thuringiensis bound fluorescein isothiocyanate-labeled antibodies specific for the 65-kDa activated Cry 1Ac toxin, whereas spores from Bacillus cereus and Cry ؊ strains of B. thuringiensis did not. The Cry ؉ spores could be activated for germination by alkaline conditions (pH 10.3), whereas Cry ؊ spores could not. Once the surrounding exosporia had been removed or permeabilized, Cry ؉ spores were able to bind the toxin receptor(s) from insect gut brush border membrane vesicle preparations, and their germination rates were increased ca. threefold in the presence of brush border membrane vesicles. A model is presented whereby in the soil the Cry toxins on the spore surface are protected by the exosporium while in the gut they are exposed and available for binding to the insect receptors. This model explains why the disulfide-rich C terminus of the cry genes is so highly conserved even though it is removed during the processing of the protoxin to the activated toxin. It also highlights the trade-off resulting from having Cry toxins located on the spore surface, i.e., decreased spore resistance versus enhanced insect pathogenesis.

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Fine Structure of the Bacillus thuringiensis Spore

Abstract: The thin-sectioned spore of Bacillus thuringiensis resembles that of Bacillus cereus in fine structure. Planar inclusions occur between the exosporium and spore coat and are structured differently from the parasporal crystal outside the exosporium.

Cited by 19 publications

References 7 publications

Resistance, germination, and permeability correlates of Bacillus megaterium spores successively divested of integument layers

Resistance, germination, and permeability correlates of Bacillus megaterium spores successively divested of integument layers

Non‐uniform assembly of the Bacillus anthracis exosporium and a bottle cap model for spore germination and outgrowth

Bacillus thuringiensis HD-73 Spores Have Surface-Localized Cry1Ac Toxin: Physiological and Pathogenic Consequences

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