Effect of Sporulation Media on the Heat Resistance of Bacillus stearothermophilus Spores1

1977 ◽  
Vol 40 (4) ◽  
pp. 232-233 ◽  
Author(s):  
J. L. MAYOU ◽  
J. J. JEZESKI
Keyword(s):  
Heat Resistance ◽  
Bacillus Stearothermophilus ◽  
Nutrient Broth ◽  
Nutrient Agar ◽  
Heat Inactivation ◽  
Vegetative Cells ◽  
Temperature Range ◽  
Heat Treated ◽  
D Values

Based on D values obtained over the temperature range of 121.1 C (250 F) to 126.7 C (260 F), Bacillus stearothermophilus vegetative cells sporulated in the presence of milk were more resistant to heat inactivation than spores grown on nutrient agar fortified with MnSo4. Spores grown in the presence of milk and heat-treated at 121.1 and 126.7 C had D values of 4.7 and 0.8 min, respectively. Spores grown on fortified nutrient agar and beat-treated at 121.1 and 126.7 C had D values of 3. 7 and 0.55 min, respectively. No difference in heat resistance was observed between spores derived from vegetative cells grown in milk or nutrient broth when tested at 121.1 C.

Effect of Using Milk as a Heating Menstruum on the Apparent Heat Resistance of Bacillus stearothermophilus Spores1

1977 ◽  
Vol 40 (4) ◽  
pp. 228-231 ◽  
Author(s):  
J. L. MAYOU ◽  
J. J. JEZESKI
Keyword(s):  
Heat Resistance ◽  
Bacillus Stearothermophilus ◽  
Survival Curves ◽  
Ph Range ◽  
D Values ◽  
D Value

Heat resistance at 121.1 C (250 F) of Bacillus stearothermophilus spores was studied using two heating menstrua. D values of 3.8 and 3.5 min were obtained when spores were heated in 0.01 M PO4 buffer, pH 6.5, and in skimmilk, pH 6.5, respectively. With buffer as a heating menstruum. increasing the pH from 6.5 to 7.2 resulted in an increase in the D value from 3.8 to 4.1 min. When the pH of skimmilk was increased from 6.5 to 7.2, D values increased from 3.5 to 5.2 min. Skimmilk as a component of the enumeration medium inhibited germination and/or outgrowth of B. stearothermophilus spores; however, this inhibition was not influenced over the pH range of 6.0 to 7.2. Addition of 10% skimmilk, pH 6.5, to the medium for enumeration of spores heated in buffer at pH 6.5 or 7.2, in each instance reduced the number of spores that could be recovered but did not change the slopes of survival curves.

Dry-heat inactivation of Bacillus subtilis var. niger spores with special reference to spore density

1976 ◽  
Vol 22 (3) ◽  
pp. 359-363 ◽  
Author(s):  
G. Molin ◽  
K. Östlund
Keyword(s):  
Bacillus Subtilis ◽  
Spore Density ◽  
Heat Inactivation ◽  
Inactivation Kinetics ◽  
Temperature Range ◽  
Dry Heat ◽  
Z Value ◽  
D Values ◽  
Kinetics Of ◽  
Spore Densities

The dry-heat inactivation kinetics of Bacillus subtilis var. niger (ATCC 9372) spores has been studied in the temperature range of 120–190 °C. The spores were applied to glass plates of a standardized area (3.24 cm2).Spore preparations of five different spore densities were used (8.3 × 104, 7.4 × 105, 7.8 × 106, 6.3 × 107, and 6.6 × 108 spores per sample, respectively). The heat resistance of the spore was dependent on the number of spores per surface unit. Maximum resistance was observed when the concentration was 7.4 × 105 spores per sample. The D-values obtained at 160 °C from these samples were about twice as high as the D-values obtained from samples with a concentration of 6.3 × 107 or 6.6 × 108 spores per sample. The z value was found to be independent of spore density. Thus, for the two concentrations 7.4 × 105 and 6.3 × 107 spores per sample, the z-value was found to be 22 °C and constant over the temperature range investigated.

Gamma-Glutamyltransferase as a Marker for the Pasteurization of Raw Milk

1998 ◽  
Vol 61 (8) ◽  
pp. 1057-1059 ◽  
Author(s):  
FILOMENA DOS ANJOS ◽  
ADELINA MACHADO ◽  
CRISTINA FERRO ◽  
FRANK OTTO ◽  
EITAN BOGIN
Keyword(s):  
Alkaline Phosphatase ◽  
Lactate Dehydrogenase ◽  
Heat Resistance ◽  
Raw Milk ◽  
Heat Inactivation ◽  
Gamma Glutamyltransferase ◽  
Complete Inactivation ◽  
Heat Treated ◽  
Commercial Kits ◽  
Raw Cow’S Milk

The degree and rate of inactivation of gamma-glutamyltransferase in raw cow's milk by heating at 50, 60,70, and 80°C for 1, 2, 3, 5, 10, 15, 20, 25, and 30 min were measured to evaluate the suitability of this enzyme as a marker for the pasteurization of milk. The enzymes alkaline phosphatase and lactate dehydrogenase were also measured under similar conditions for comparison. The patterns of heat inactivation of gamma-glutamyltransferase and alkaline phosphatase were similar, with only a minimal inactivation of the enzymes at 50°C. The rate of inactivation increased as a result of increasing temperatures and time. A complete inactivation of both enzymes was seen at 70°C after 10 min and at 80°C after 1 min. Lactate dehydrogenase showed a higher heat resistance with almost complete inactivation at 70°C for 30 min, and compete inactivation at 80°C for 3 min. No activities of these enzymes were found in commercially pasteurized or heat-treated milk. The levels of gamma-glutamyltransferase in raw milk were between 8 and 10% higher than those of alkaline phosphatase and lactate dehydrogenase, making it more sensitive and accurate as a testing marker. It seems that gamma-glutamyltransferase may serve as a good pasteurization marker. Furthermore, the simplicity of testing and the availability of commercial kits for testing by both wet and dry chemistry make it an attractive choice, especially because dry chemistry procedures overcome the difficulties originating from the turbidity of milk, which interferes with spectrophotometric procedures.

Thermal Resistance of Bacillus stearothermophilus Spores Heated in Acidified Mushroom Extract

1994 ◽  
Vol 57 (1) ◽  
pp. 37-41 ◽  
Author(s):  
PABLO S. FERNANDEZ ◽  
MARIA J. OCIO ◽  
TOMAS SANCHEZ ◽  
ANTONIO MARTINEZ
Keyword(s):  
Citric Acid ◽  
Thermal Resistance ◽  
Heat Resistance ◽  
Bacillus Stearothermophilus ◽  
Ph Effect ◽  
Bidistilled Water ◽  
Mushroom Extract ◽  
Reference Medium ◽  
D Values

The thermal resistance of Bacillus stearothermophilus spores was studied in bidistilled water as the reference medium, mushroom extract and acidified mushroom extract. Citric acid and glucono-δ-lactone were used as acidulants. Results indicated that mushroom extract affects the heat resistance of spores; D values were lower than for those in bidistilled water. The pH effect was lower with higher treatment temperatures. Acidification reduced the thermal resistance of spores, the reduction being similar for both types of acidulants, and in general it also had the effect of increasing the z values. It has been confirmed that acidification of the canned mushrooms could actually help to control the thermophilic spoilage. This acidification could also be obtained by the use of glucono-δ-lactone, which has been shown to be as effective as citric acid in reducing the heat resistance of spores.

D Values of Bacillus stearothermophilus Spores as a Function of pH and Recovery Medium Acidulant

1995 ◽  
Vol 58 (6) ◽  
pp. 628-632 ◽  
Author(s):  
P. S. FERNÁNDEZ ◽  
F. J. GÓMEZ ◽  
M. J. OCIO ◽  
M. RODRIGO ◽  
T. SÁNCHEZ ◽  
...  
Keyword(s):  
Citric Acid ◽  
Thermal Resistance ◽  
Bacillus Stearothermophilus ◽  
Great Influence ◽  
Bidistilled Water ◽  
Mushroom Extract ◽  
Heat Treated ◽  
Reference Medium ◽  
D Values ◽  
Recovery Medium

The effect of the pH and the type of acidulant (citric acid or glucono-δ-lactone) of the recovery medium on the thermal resistance of Bacillus stearothermophilus ATCC 12980 was studied. The spores were heated in bidistilled water as a reference substrate and in acidified mushroom extract using citric acid or glucono-δ-lactone as acidulants (pH 6.2) and subcultured in reference (pH 7) and acidified (pH 6.2) media. A period of treatment-dependent pH sensitization was observed in heat-treated spores. In all cases, D values were lower in the acidified recovery medium than those obtained in the reference medium, but the type of acidulant used in the recovery medium had no influence on the D values. No influence on z values was observed as a consequence of the different recovery media, but they changed within a range of 7 to 10°C as a function of the different heating substrates. Glucono-δ-lactone proved to be as effective as citric acid in controlling the microbiological spoilage of foods. The pH has a great influence on decreasing the D values, mainly when acidification of the substrate and acidification of the recovery medium are combined. Consequently, it would be appropriate to take this effect into account in process calculations or validation.

Heat Resistance of Vegetative Cells and Asci of Two Zygosaccharomyces Yeasts in Broths at Different Water Activity Values

1987 ◽  
Vol 50 (10) ◽  
pp. 835-841 ◽  
Author(s):  
MARCO F. G. JERMINI ◽  
WILHELM SCHMIDT-LORENZ
Keyword(s):  
Heat Resistance ◽  
Water Activity ◽  
Vegetative Cells ◽  
Decimal Reduction Time ◽  
Reduction Time ◽  
Zygosaccharomyces Rouxii ◽  
Heat Resistant ◽  
Cell Material ◽  
C Value ◽  
D Values

The heat resistance of vegetative cells and asci of two osmotolerant yeasts (Zygosaccharomyces rouxii and Z. bailii) was investigated in two different broths of aw 0.963 and 0.858, respectively. The highest heat resistance was observed with asci of Z. bailii LMZ 108, showing a decimal reduction time (D-value) at 60°C and aw 0.858 of 14.9 min. Asci of Z. rouxii LMZ 100 were less heat resistant (D60°C-value at aw 0.858 = 3.5 min). The heat resistance (D-values) of asci at aw 0.963 proved to be 20- to 50-fold and 5- to 8-fold higher than the D-valucs of the corresponding vegetative cells of Z. rouxii and Z. bailii, respectively. However, the lower the aw of the heating broth, the smaller the differences between heat resistance of asci and that of vegetative cells. Morever, different preparations of the same cell material were found to lead to different heat resistances.

Simple Technique to Determine Heat Resistance of Bacillus stearothermophilus Spores in Fluid Systems1

1980 ◽  
Vol 43 (10) ◽  
pp. 799-804 ◽  
Author(s):  
E. M. MIKOLAJCIK ◽  
KATHLEEN T. RAJKOWSKI
Keyword(s):  
Heat Resistance ◽  
Soy Protein ◽  
Milk Protein ◽  
Bacillus Stearothermophilus ◽  
Capillary Tube ◽  
Serum Bottle ◽  
Maximum Heat ◽  
Heat Activation ◽  
The Difference ◽  
D Values

A simple, rapid, highly reproducible procedure was developed to determine heat resistance of Bacillus stearothermophilus spores in milk and soy protein-based formulas at temperatures > 100 C. Plating efficiencies on different media and heat activation temperatures were also studied. The procedure involved use of a serum bottle to which was added formula. The bottle was closed with a rubber septum and sealed air-tight with a crimped aluminum cap. The formula was agitated during heating in a thermostatically controlled oil bath, using a wrist action shaker. When the formula attained the desired temperature, a spore suspension was injected through the rubber septum, using a high-pressure GLC syringe. At selected time intervals, a portion was withdrawn from the bottle, using a sterile GLC syringe. The number of surviving spores was determined by plating on Trypticase Soy agar, which yielded significantly higher spore recovery count than did Trypticase Soy broth fortified with 1.5% agar with and without starch, or Dextrose Tryptone agar. The serum bottle procedure yielded higher D values than did the capillary tube procedure. The difference was significant where p = 0.05 but not where p = 0.01. With the serum bottle procedure, D values for spores in the milk protein base formula were 18.46, 3.56 and 1.13 min at 115, 121 and 125 C, respectively. In the soy protein base formula, D values were 26.1, 3.64 and 1.26 min, respectively. The z values were 7.7 and 7.6 Centigrade degrees (13.86 and 13.68 Fahrenheit degrees). Maximum heat activation of the spore was at 95 C for 10 min in milk protein base formula and at 100 C for 5 min in the soy product.

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

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.

Modeling the Effects of Temperature, Sodium Chloride, and Green Tea and Their Interactions on the Thermal Inactivation of Listeria monocytogenes in Turkey†

2014 ◽  
Vol 77 (10) ◽  
pp. 1696-1702 ◽  
Author(s):  
VIJAY K. JUNEJA ◽  
JIMENA GARCIA-DÁVILA ◽  
JULIO CESAR LOPEZ-ROMERO ◽  
ETNA AIDA PENA-RAMOS ◽  
JUAN PEDRO CAMOU ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Sodium Chloride ◽  
Protective Effect ◽  
Heat Resistance ◽  
Green Tea ◽  
Thermal Inactivation ◽  
Heating Temperature ◽  
Lethal Effect ◽  
Interactive Effects ◽  
D Values

The interactive effects of heating temperature (55 to 65°C), sodium chloride (NaCl; 0 to 2%), and green tea 60% polyphenol extract (GTPE; 0 to 3%) on the heat resistance of a five-strain mixture of Listeria monocytogenes in ground turkey were determined. Thermal death times were quantified in bags that were submerged in a circulating water bath set at 55, 57, 60, 63, and 65°C. The recovery medium was tryptic soy agar supplemented with 0.6% yeast extract and 1% sodium pyruvate. D-values were analyzed by second-order response surface regression for temperature, NaCl, and GTPE. The data indicated that all three factors interacted to affect the inactivation of the pathogen. The D-values for turkey with no NaCl or GTPE at 55, 57, 60, 63, and 65°C were 36.3, 20.8, 13.2, 4.1, and 2.9 min, respectively. Although NaCl exhibited a concentration-dependent protective effect against heat lethality on L. monocytogenes in turkey, addition of GTPE rendered the pathogen more sensitive to the lethal effect of heat. GTPE levels up to 1.5% interacted with NaCl and reduced the protective effect of NaCl on heat resistance of the pathogen. Food processors can use the predictive model to design an appropriate heat treatment that would inactivate L. monocytogenes in cooked turkey products without adversely affecting the quality of the product.

Modeling Penicillium expansum Resistance to Thermal and Chlorine Treatments

2009 ◽  
Vol 72 (12) ◽  
pp. 2618-2622 ◽  
Author(s):  
BEATRIZ C. M. SALOMÃO ◽  
JOHN J. CHUREY ◽  
GLÁUCIA M. F. ARAGÃO ◽  
RANDY W. WOROBO
Keyword(s):  
Apple Juice ◽  
Weibull Model ◽  
Superior Performance ◽  
Penicillium Expansum ◽  
Heat Inactivation ◽  
Survival Curves ◽  
Biphasic Model ◽  
Log Reduction ◽  
Weibull Models ◽  
D Values

Apples and apple products are excellent substrates for Penicillium expansum to produce patulin. In an attempt to avoid excessive levels of patulin, limiting or reducing P. expansum contamination levels on apples designated for storage in packinghouses and/or during apple juice processing is critical. The aim of this work was (i) to determine the thermal resistance of P. expansum spores in apple juice, comparing the abilities of the Bigelow and Weibull models to describe the survival curves and (ii) to determine the inactivation of P. expansum spores in aqueous chlorine solutions at varying concentrations of chlorine solutions, comparing the abilities of the biphasic and Weibull models to fit the survival curves. The results showed that the Bigelow and Weibull models were similar for describing the heat inactivation data, because the survival curves were almost linear. In this case, the concept of D- and z-values could be used, and the D-values obtained were 10.68, 6.64, 3.32, 1.14, and 0.61 min at 50, 52, 54, 56, and 60°C, respectively, while the z-value was determined to be 7.57°C. For the chlorine treatments, although the biphasic model gave a slightly superior performance, the Weibull model was selected, considering the parsimony principle, because it has fewer parameters than the biphasic model has. In conclusion, the typical pasteurization regimen used for refrigerated apple juice (71°C for 6 s) is capable of achieving a 6-log reduction of P. expansum spores.

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