scholarly journals Heat activation and inactivation of bacterial spores. Is there an overlap?

2022 ◽  
Author(s):  
Juan Wen ◽  
Jan P. P. M. Smelt ◽  
Norbert O.E. Vischer ◽  
Arend L. de Vos ◽  
Peter Setlow ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Spore Germination ◽  
Bacterial Spores ◽  
Heat Inactivation ◽  
Dependent Manner ◽  
Single Spore ◽  
Heat Damage ◽  
Heat Resistant ◽  
New Information ◽  
Heat Activation

Heat activation at a sublethal temperature is widely applied to promote Bacillus species spore germination. This treatment also has 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 40-80°C, and for 0-300 min. The results were as follows. 1) Heat activation at 40-70°C promoted L-valine and L-asparagine-glucose-fructose-potassium (AGFK) induced germination in a time dependent manner. 2) The optimal heat activation temperatures for AGFK and L-valine germination via the GerB plus GerK or GerA germinant receptors were 65 and 50-65°C, respectively. 3) 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. 4) 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. 5) For the spores that should withstand adverse environmental temperatures in nature, heat activation seems functional for a subsequent optimal germination process, while heat damage affected both germination and outgrowth. Importance Bacterial spores are thermal resistant structures that can thus survive preservation strategies and revive through the process of spore germination. The more heat resistant spores are the more heterogeneous they germinate upon adding germinants. Upon germination spores can cause food spoilage and cause food intoxication. Here we provide new information on both heat activation and inactivation regimes and their effects on the (heterogeneity of) spore germination.

scholarly journals Heat activation and inactivation of bacterial spores. Is there an overlap?

2021 ◽  
Author(s):  
Juan Wen ◽  
Jan P.P.M. Smelt ◽  
Norbert O.E. Vischer ◽  
Arend D Vos ◽  
Peter Setlow ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Spore Germination ◽  
Bacterial Spores ◽  
Heat Inactivation ◽  
Bacillus Species ◽  
Dependent Manner ◽  
Single Spore ◽  
Heat Damage ◽  
Germination Process ◽  
Heat Activation

Heat activation at a sublethal temperature is widely applied to promote Bacillus species spore germination. This treatment also has 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 40-80 degrees Celcius, and for 0-300 min. The results were as follows. 1) Heat activation at 40-70 degrees Celcius promoted L-valine and L-asparagine-glucose-fructose-potassium (AGFK) induced germination in a time dependent manner. 2) The optimal heat activation temperatures for AGFK and L-valine germination via the GerB plus GerK or GerA germinant receptors were 65 and 50-65 degrees Celcius, respectively. 3) Heat inactivation of dormant spores appeared at 70 degrees Celcius, and the heat damage of molecules essential for germination and growth began at 70 and 65 degrees Celcius, respectively. 4) Heat treatment at 75 degrees Celcius resulted in both activation of germination and damage to the germination apparatus, and 80 degrees Celcius treatment caused more pronounced heat damage. 5) For the spores that should withstand adverse environmental temperatures in nature, heat activation seems functional for a subsequent optimal germination process, while heat damage affected both germination and outgrowth.

Promoting Bacillus cereus Spore Germination for Subsequent Inactivation by Mild Heat Treatment

2011 ◽  
Vol 74 (12) ◽  
pp. 2079-2089 ◽  
Author(s):  
IRENE STRANDEN LØVDAL ◽  
MARIA BEFRING HOVDA ◽  
PER EINAR GRANUM ◽  
JAN THOMAS ROSNES
Keyword(s):  
Heat Treatment ◽  
Bacillus Cereus ◽  
Spore Germination ◽  
Heat Inactivation ◽  
Mild Heat ◽  
Heat Treated ◽  
Conventional Heat Treatment ◽  
Heat Activation ◽  
Treatment Procedures ◽  
Double Heat Treatment

Sublethal heat treatment may activate dormant spores and thereby potentiate the conversion of spores to vegetative cells. As the germinated spore is known to possess lower heat resistance than its dormant counterpart, it has been postulated that double heat treatment, i.e., spore heat activation followed by germination and then by heat inactivation, can be used to control spores in foods. Production of refrigerated processed foods of extended durability often includes more than one heat treatment of the food components. This work simulates conventional heat treatment procedures and evaluates double heat treatment as a method to improve spore control in model food matrixes of meat broth and cream sauce. Bacillus cereus NVH 1230-88 spores were supplemented in food model matrixes and heat activated at 70°C and then heat inactivated at 80 or 90°C. The samples were held at 29 to 30°C for 1 h between primary and secondary heat treatments, to allow spore germination. Nutrients naturally present in the food matrixes, e.g., amino acids and inosine, could act as germinants that induce germination. The levels of germinants could be too low to produce effective germination within 1 h. Following primary heat treatment, some samples were therefore supplemented with a combination of L-alanine and inosine, a germinant mixture known to be effective for B. cereus spores. In both matrixes, a combination of double heat treatment (heat activation, germination, and inactivation) and addition of germinants gave a reduction in spore counts equivalent to or greater than that obtained with a single heat treatment for 12 min at 90°C. Addition of germinants was essential to induce effective germination in cream sauce during 1 h at 29 to 30°C, and germinants were therefore a crucial supplement to obtain an effect of double heat treatment in this matrix. These data will be valuable when setting up temperature-time-germinant combinations for an optimized spore reduction in mild-heat–treated foods.

scholarly journals Analysis of Germination Capacity and Germinant Receptor (Sub)clusters of Genome-Sequenced Bacillus cereus Environmental Isolates and Model Strains

2016 ◽  
Vol 83 (4) ◽  
Author(s):  
Alicja K. Warda ◽  
Yinghua Xiao ◽  
Jos Boekhorst ◽  
Marjon H. J. Wells-Bennik ◽  
Masja N. Nierop Groot ◽  
...  
Keyword(s):  
Bacillus Cereus ◽  
Spore Germination ◽  
Brain Heart Infusion ◽  
Whole Genome Sequence ◽  
Single Spore ◽  
Content Type ◽  
Germination Response ◽  
Natural Isolates ◽  
Heat Activation ◽  
Different Strains

ABSTRACT Spore germination of 17 Bacillus cereus food isolates and reference strains was evaluated using flow cytometry analysis in combination with fluorescent staining at a single-spore level. This approach allowed for rapid collection of germination data under more than 20 conditions, including heat activation of spores, germination in complex media (brain heart infusion [BHI] and tryptone soy broth [TSB]), and exposure to saturating concentrations of single amino acids and the combination of alanine and inosine. Whole-genome sequence comparison revealed a total of 11 clusters of operons encoding germinant receptors (GRs): GerK, GerI, and GerL were present in all strains, whereas GerR, GerS, GerG, GerQ, GerX, GerF, GerW, and GerZ (sub)clusters showed a more diverse presence/absence in different strains. The spores of tested strains displayed high diversity with regard to their sensitivity and responsiveness to selected germinants and heat activation. The two laboratory strains, B. cereus ATCC 14579 and ATCC 10987, and 11 food isolates showed a good germination response under a range of conditions, whereas four other strains (B. cereus B4085, B4086, B4116, and B4153) belonging to phylogenetic group IIIA showed a very weak germination response even in BHI and TSB media. Germination responses could not be linked to specific (combinations of) GRs, but it was noted that the four group IIIA strains contained pseudogenes or variants of subunit C in their gerL cluster. Additionally, two of those strains (B4086 and B4153) carried pseudogenes in the gerK and gerR I (sub)clusters that possibly affected the functionality of these GRs. IMPORTANCE Germination of bacterial spores is a critical step before vegetative growth can resume. Food products may contain nutrient germinants that trigger germination and outgrowth of Bacillus species spores, possibly leading to food spoilage or foodborne illness. Prediction of spore germination behavior is, however, very challenging, especially for spores of natural isolates that tend to show more diverse germination responses than laboratory strains. The approach used has provided information on the genetic diversity in GRs and corresponding subclusters encoded by B. cereus strains, as well as their germination behavior and possible associations with GRs, and it provides a basis for further extension of knowledge on the role of GRs in B. cereus (group member) ecology and transmission to the host.

scholarly journals Spore Heat Activation Requirements and Germination Responses Correlate with Sequences of Germinant Receptors and with the Presence of a Specific spoVA2mob Operon in Foodborne Strains of Bacillus subtilis

2017 ◽  
Vol 83 (7) ◽  
Author(s):  
Antonina O. Krawczyk ◽  
Anne de Jong ◽  
Jimmy Omony ◽  
Siger Holsappel ◽  
Marjon H. J. Wells-Bennik ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Heat Resistance ◽  
Spore Germination ◽  
Food Industry ◽  
Heat Treatments ◽  
Phenotypic Traits ◽  
Content Type ◽  
Heat Resistant ◽  
Heat Activation ◽  
High Level

ABSTRACT Spore heat resistance, germination, and outgrowth are problematic bacterial properties compromising food safety and quality. Large interstrain variation in these properties makes prediction and control of spore behavior challenging. High-level heat resistance and slow germination of spores of some natural Bacillus subtilis isolates, encountered in foods, have been attributed to the occurrence of the spoVA 2mob operon carried on the Tn1546 transposon. In this study, we further investigate the correlation between the presence of this operon in high-level-heat-resistant spores and their germination efficiencies before and after exposure to various sublethal heat treatments (heat activation, or HA), which are known to significantly improve spore responses to nutrient germinants. We show that high-level-heat-resistant spores harboring spoVA 2mob required higher HA temperatures for efficient germination than spores lacking spoVA 2mob. The optimal spore HA requirements additionally depended on the nutrients used to trigger germination, l-alanine (l-Ala), or a mixture of l-asparagine, d-glucose, d-fructose, and K+ (AGFK). The distinct HA requirements of these two spore germination pathways are likely related to differences in properties of specific germinant receptors. Moreover, spores that germinated inefficiently in AGFK contained specific changes in sequences of the GerB and GerK germinant receptors, which are involved in this germination response. In contrast, no relation was found between transcription levels of main germination genes and spore germination phenotypes. The findings presented in this study have great implications for practices in the food industry, where heat treatments are commonly used to inactivate pathogenic and spoilage microbes, including bacterial spore formers. IMPORTANCE This study describes a strong variation in spore germination capacities and requirements for a heat activation treatment, i.e., an exposure to sublethal heat that increases spore responsiveness to nutrient germination triggers, among 17 strains of B. subtilis, including 9 isolates from spoiled food products. Spores of industrial foodborne isolates exhibited, on average, less efficient and slower germination responses and required more severe heat activation than spores from other sources. High heat activation requirements and inefficient, slow germination correlated with elevated resistance of spores to heat and with specific genetic features, indicating a common genetic basis of these three phenotypic traits. Clearly, interstrain variation and numerous factors that shape spore germination behavior challenge standardization of methods to recover highly heat-resistant spores from the environment and have an impact on the efficacy of preservation techniques used by the food industry to control spores.

scholarly journals Elevating body temperature enhances hematopoiesis and neutrophil recovery after total body irradiation in an IL-1–, IL-17–, and G-CSF–dependent manner

Blood ◽  
2012 ◽  
Vol 120 (13) ◽  
pp. 2600-2609 ◽  
Author(s):  
Maegan L. Capitano ◽  
Michael J. Nemeth ◽  
Thomas A. Mace ◽  
Christi Salisbury-Ruf ◽  
Brahm H. Segal ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Bone Marrow ◽  
Body Temperature ◽  
Total Body Irradiation ◽  
Dependent Manner ◽  
Intestinal Tissue ◽  
Hematopoietic Stem ◽  
Neutrophil Recovery ◽  
Total Body ◽  
The Impact

Abstract Neutropenia is a common side effect of cytotoxic chemotherapy and radiation, increasing the risk of infection in these patients. Here we examined the impact of body temperature on neutrophil recovery in the blood and bone marrow after total body irradiation (TBI). Mice were exposed to either 3 or 6 Gy TBI followed by a mild heat treatment that temporarily raised core body temperature to approximately 39.5°C. Neutrophil recovery was then compared with control mice that received either TBI alone heat treatment alone. Mice that received both TBI and heat treatment exhibited a significant increase in the rate of neutrophil recovery in the blood and an increase in the number of marrow hematopoietic stem cells and neutrophil progenitors compared with that seen in mice that received either TBI or heat alone. The combination treatment also increased G-CSF concentrations in the serum, bone marrow, and intestinal tissue and IL-17, IL-1β, and IL-1α concentrations in the intestinal tissue after TBI. Neutralizing G-CSF or inhibiting IL-17 or IL-1 signaling significantly blocked the thermally mediated increase in neutrophil numbers. These findings suggest that a physiologically relevant increase in body temperature can accelerate recovery from neutropenia after TBI through a G-CSF–, IL-17–, and IL-1–dependent mechanism.

The Impact of Heat Treatment on Pyrophyllite Structure and Acid-Soluble Properties

2011 ◽  
Vol 366 ◽  
pp. 326-329 ◽  
Author(s):  
Jun Jun Wu ◽  
Hai Feng Chen ◽  
Shi Jiang Zhao ◽  
Bin Li
Keyword(s):  
Heat Treatment ◽  
Thermal Activation ◽  
Acid Leaching ◽  
Basic Structure ◽  
Hydrochloric Acid Concentration ◽  
Activation Temperature ◽  
Different Temperatures ◽  
Ft Ir ◽  
Heat Activation ◽  
The Impact

This paper studied the influence of heat treatment on the pyrophyllite structure and acid-soluble properties of alumina. Qualitative tests had been performed in studying pyrophyllite crystal at different temperatures by XRD, TG-DTA, FT-IR and quantitative analysis of Al2O3. The quantitative titration method studied the dissolve characteristics of the different heat treatment samples in different acid conditions, and then a numerical simulation was done. The results showed that at temperatures below 480 °C, the pyrophyllite did not change the basic structure. 480~700 °C dehydroxylation reaction occurred, and the structure water of pyrophyllite is removed, and then turned into partial pyrophyllite. Dissolution experiments showed that after thermal activation the behavior of alumina in acid the dissolution was different, which was affected by hydrochloric acid concentration, heat activation temperature and acid leaching time. When the calcinations temperature was 700 °C, the dissolution amount of alumina was largest. These works could provide some theoretical basis for further application of pyrophyllite research.

An aniline-substituted bile salt analog protects both mice and hamsters from multiple Clostridioides difficile strains

2021 ◽  
Author(s):  
Jacqueline R. Phan ◽  
Dung M. Do ◽  
Minh Chau Truong ◽  
Connie Ngo ◽  
Julian H. Phan ◽  
...  
Keyword(s):  
Bile Salt ◽  
Spore Germination ◽  
Dependent Manner ◽  
Germination Inhibitors ◽  
New Methods ◽  
Clostridioides Difficile ◽  
Antibiotic Associated Diarrhea ◽  
Careful Screening ◽  
Strain Dependent

Clostridioides difficile infection (CDI) is the major identifiable cause of antibiotic-associated diarrhea. The emergence of hypervirulent C. difficile strains has led to increases in both hospital- and community-acquired CDI. Furthermore, CDI relapse from hypervirulent strains can reach up to 25%. Thus, standard treatments are rendered less effective, making new methods of prevention and treatment more critical. Previously, the bile salt analog CamSA was shown to inhibit spore germination in vitro and protect mice and hamsters from C. difficile strain 630. Here, we show that CamSA was less active at preventing spore germination of other C. difficile ribotypes, including the hypervirulent strain R20291. Strain-specific in vitro germination activity of CamSA correlated with its ability to prevent CDI in mice. Additional bile salt analogs were screened for in vitro germination inhibition activity against strain R20291, and the most active compounds were tested against other strains. An aniline-substituted bile salt analog, (CaPA), was found to be a better anti-germinant than CamSA against eight different C. difficile strains. In addition, CaPA was capable of reducing, delaying, or preventing murine CDI signs in all strains tested. CaPA-treated mice showed no obvious toxicity and showed minor effects on their gut microbiome. CaPA’s efficacy was further confirmed by its ability to prevent CDI in hamsters infected with strain 630. These data suggest that C. difficile spores respond to germination inhibitors in a strain-dependent manner. However, careful screening can identify anti-germinants with broad CDI prophylaxis activity.

Heat Treatment of Heat-Resistant Ferrous Cast Alloys

2015 ◽  
Vol 9 (2) ◽  
pp. 7-20 ◽  
Author(s):  
Delin Li ◽  
Clayton Sloss
Keyword(s):  
Heat Treatment ◽  
Heat Resistant ◽  
Cast Alloys

Heat shock increases cytosolic free Ca2+ concentration via Na(+)-Ca2+ exchange in human epidermoid A 431 cells

1992 ◽  
Vol 263 (1) ◽  
pp. C30-C38 ◽  
Author(s):  
J. G. Kiang ◽  
M. L. Koenig ◽  
R. C. Smallridge
Keyword(s):  
Heat Treatment ◽  
Heat Shock ◽  
Time Dependent ◽  
Maximal Velocity ◽  
Dependent Manner ◽  
Michaelis Constant ◽  
Exchange System ◽  
Maximal Increase ◽  
Normal Cells ◽  
Dimethyl Amiloride

This study characterized cytosolic free Ca2+ concentration ([Ca2+]i) in normal and thermally injured human epidermoid A 431 cells. The resting [Ca2+]i in normal cells at 37 degrees C was 87 +/- 5 nM (n = 105). When cells were subjected to hyperthermia (40-50 degrees C), [Ca2+]i increased in a temperature- and time-dependent manner. The maximal increase in cells exposed to 45 degrees C was observed at 20 min; [Ca2+]i returned to normal within 1 h. The heat-induced [Ca2+]i increase depended on the presence of external Ca2+. La3+ and Cd2+ but not Co2+, verapamil, or nifedipine attenuated the heat-induced [Ca2+]i increase. TMB-8 partially blocked the increase in [Ca2+]i but pertussis toxin and cholera toxin pretreatment did not. The magnitude of the heat-induced [Ca2+]i increase or 45Ca2+ uptake depended on the presence of extracellular Na+. Heat treatment reduced the apparent Michaelis constant for external Ca2+ from 490 +/- 91 to 210 +/- 60 microM, whereas the maximal velocity remained the same. The intracellular Na+ concentration decreased 62.5% after heating. The heat-induced [Ca2+]i increase was completely blocked by amiloride (5 microM) and 5'-(N,N-dimethyl)-amiloride (1 microM). These results suggest heat activates the Na(+)-Ca2+ exchange system so as to increase [Ca2+]i and reduce [Na+]i.

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