Factors Contributing to Heat Resistance of Clostridium perfringens Endospores

ABSTRACT The endospores formed by strains of type A Clostridium perfringens that produce the C. perfringens enterotoxin (CPE) are known to be more resistant to heat and cold than strains that do not produce this toxin. The high heat resistance of these spores allows them to survive the cooking process, leading to a large number of food-poisoning cases each year. The relative importance of factors contributing to the establishment of heat resistance in this species is currently unknown. The present study examines the spores formed by both CPE+ and CPE− strains for factors known to affect heat resistance in other species. We have found that the concentrations of DPA and metal ions, the size of the spore core, and the protoplast-to-sporoplast ratio are determining factors affecting heat resistance in these strains. While the overall thickness of the spore peptidoglycan was found to be consistent in all strains, the relative amounts of cortex and germ cell wall peptidoglycan also appear to play a role in the heat resistance of these strains.

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A Putative Amidase Endolysin Encoded by Clostridium perfringens St13 Exhibits Specific Lytic Activity and Synergizes with the Muramidase Endolysin Psm

Antibiotics ◽

10.3390/antibiotics10030245 ◽

2021 ◽

Vol 10 (3) ◽

pp. 245

Author(s):

Hiroshi Sekiya ◽

Maho Okada ◽

Eiji Tamai ◽

Toshi Shimamoto ◽

Tadashi Shimamoto ◽

...

Keyword(s):

Cell Wall ◽

Clostridium Perfringens ◽

Antimicrobial Agents ◽

Catalytic Domain ◽

Food Poisoning ◽

Binding Activity ◽

Lytic Activity ◽

Intestinal Bacterium ◽

Terminal Domain ◽

Cell Wall Binding

Clostridium perfringens is an often-harmful intestinal bacterium that causes various diseases ranging from food poisoning to life-threatening fulminant disease. Potential treatments include phage-derived endolysins, a promising family of alternative antimicrobial agents. We surveyed the genome of the C. perfringens st13 strain and identified an endolysin gene, psa, in the phage remnant region. Psa has an N-terminal catalytic domain that is homologous to the amidase_2 domain, and a C-terminal domain of unknown function. psa and gene derivatives encoding various Psa subdomains were cloned and expressed in Escherichia coli as N-terminal histidine-tagged proteins. Purified His-tagged full-length Psa protein (Psa-his) showed C. perfringens-specific lytic activity in turbidity reduction assays. In addition, we demonstrated that the uncharacterized C-terminal domain has cell wall-binding activity. Furthermore, cell wall-binding measurements showed that Psa binding was highly specific to C. perfringens. These results indicated that Psa is an amidase endolysin that specifically lyses C. perfringens; the enzyme’s specificity is highly dependent on the binding of the C-terminal domain. Moreover, Psa was shown to have a synergistic effect with another C. perfringens-specific endolysin, Psm, which is a muramidase that cleaves peptidoglycan at a site distinct from that targeted by Psa. The combination of Psa and Psm may be effective in the treatment and prevention of C. perfringens infections.

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Clustering rooting for the high heat resistance of some CHNO energetic materials

FirePhysChem ◽

10.1016/j.fpc.2021.02.007 ◽

2021 ◽

Vol 1 (1) ◽

pp. 8-20

Author(s):

Xingyu Huo ◽

Fanfan Wang ◽

Liang Liang Niu ◽

Ruijun Gou ◽

Chaoyang Zhang

Keyword(s):

Heat Resistance ◽

Energetic Materials ◽

High Heat ◽

High Heat Resistance

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Molecular Physiological Characterization of a High Heat Resistant Spore Forming Bacillus subtilis Food Isolate

Microorganisms ◽

10.3390/microorganisms9030667 ◽

2021 ◽

Vol 9 (3) ◽

pp. 667

Author(s):

Zhiwei Tu ◽

Peter Setlow ◽

Stanley Brul ◽

Gertjan Kramer

Keyword(s):

Bacillus Subtilis ◽

Heat Resistance ◽

Dipicolinic Acid ◽

Laboratory Strain ◽

High Heat ◽

High Heat Resistance ◽

Vegetative Cells ◽

Heat Resistant ◽

Food Isolate ◽

Wet Heat

Bacterial endospores (spores) are among the most resistant living forms on earth. Spores of Bacillus subtilis A163 show extremely high resistance to wet heat compared to spores of laboratory strains. In this study, we found that spores of B. subtilis A163 were indeed very wet heat resistant and released dipicolinic acid (DPA) very slowly during heat treatment. We also determined the proteome of vegetative cells and spores of B. subtilis A163 and the differences in these proteomes from those of the laboratory strain PY79, spores of which are much less heat resistant. This proteomic characterization identified 2011 proteins in spores and 1901 proteins in vegetative cells of B. subtilis A163. Surprisingly, spore morphogenic protein SpoVM had no homologs in B. subtilis A163. Comparing protein expression between these two strains uncovered 108 proteins that were differentially present in spores and 93 proteins differentially present in cells. In addition, five of the seven proteins on an operon in strain A163, which is thought to be primarily responsible for this strain’s spores high heat resistance, were also identified. These findings reveal proteomic differences of the two strains exhibiting different resistance to heat and form a basis for further mechanistic analysis of the high heat resistance of B. subtilis A163 spores.

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