Heat activation at a sublethal temperature is widely applied to promote species spore germination. This treatment also has the potential to be employed in food processing to eliminate undesired bacterial spores by enhancing their germination and then inactivating the less-heat-resistant germinated spores at a milder temperature. However, incorrect heat treatment could also generate heat damage in spores and lead to more heterogeneous spore germination. Here, the heat activation and heat damage profile of Bacillus subtilis spores was determined by testing spore germination and outgrowth at both population and single-spore levels. The heat treatments used were 40 to 80°C and for 0 to 300 min. The results were as follows. (i) Heat activation at 40 to 70°C promoted l-valine- and l-asparagine-glucose-fructose-potassium (AGFK)-induced germination in a time-dependent manner. (ii) The optimal heat activation temperatures for AGFK and l-valine germination via the GerB plus GerK or GerA germinant receptors were 65°C and 50 to 65°C, respectively. (iii) Heat inactivation of dormant spores appeared at 70°C, and the heat damage of molecules essential for germination and growth began at 70 and 65°C, respectively. (iv) Heat treatment at 75°C resulted in both activation of germination and damage to the germination apparatus, and 80°C treatment caused more pronounced heat damage. (v) For the spores that should withstand adverse environmental temperatures in nature, heat activation seemed functional for a subsequent optimal germination process, while heat damage affected both germination and outgrowth. Bacterial spores are thermal-stress-resistant structures that can thus survive food preservation strategies and revive through the process of spore germination. The more heat resistant spores are, the more heterogeneous their germination upon the addition of germinants. Upon germination, spores can cause food spoilage and food intoxication. Here, we provide new information on both heat activation and inactivation regimes and their effects on the (heterogeneity of) spore germination.
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http://dx.doi.org/10.1128/aem.02324-21 | DOI Listing |
Nat Struct Mol Biol
January 2025
Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA.
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Graduate Program in Food Science and Technology, Federal University of Paraíba, 58051-900 João Pessoa, Paraíba, Brazil. Electronic address:
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View Article and Find Full Text PDFEnviron Int
January 2025
Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, Beijing 100191, China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, School of Public Health, Peking University, Beijing 100083, China.
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View Article and Find Full Text PDFMicrobiol Res
January 2025
Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture and Rural Affairs, PR China; Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, Jiangsu, PR China. Electronic address:
Heat stress is a prevalent environmental stressor. Previous studies have shown that heat stress drives many cellular changes in Ganoderma lucidum. Interestingly, glycolysis is activated during heat stress, which could contribute to increased heat resistance.
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