Heat Resistance of Bacillus subtilis in Buffer and Foods of Different pH

1992 ◽  
Vol 55 (8) ◽  
pp. 605-608 ◽  
Author(s):  
SANTIAGO CONDON ◽  
FRANCISCO J. SALA
Keyword(s):  
Bacillus Subtilis ◽  
Heat Resistance ◽  
Continuous Monitoring ◽  
Effect Of Ph ◽  
Mcilvaine Buffer ◽  
Ph Values ◽  
Z Value ◽  
Influence Of Ph

Heat resistance of a strain of Bacillus subtilis was measured in homogenized canned mushrooms, peas, lentils, meat balls, and tomato; in rehydrated potato purée; and in buffer at selected pH values, to detect any influence of pH and/or-menstruum upon heat resistance. Heat resistance experiments were carried out under continuous monitoring of pH. Dt = 1 min in buffer at pH 4.2, 5.2, 6.1, and 7.1 was obtained at 89.1, 97.3, 104.4, and 107.1°C, respectively. The effect of pH was lower the higher the temperature of treatment. The z values ranged from 6.4 at pH 7.1 to 10.3 at pH 4.2. Heat resistance was mainly dependent on pH of food, but an influence of the food itself was also observed. The pH influenced z value in McIlvaine buffer but not in foods. Prediction of heat resistance values in foods from data obtained in buffer at the same pH is unadvisable as it may lead to errors. These errors will become greater in acid foods the higher the temperature of treatment.

Sporulation Temperature and Heat Resistance of Bacillus subtilis at Different pH Values

1995 ◽  
Vol 58 (3) ◽  
pp. 239-243 ◽  
Author(s):  
FRANCISCO J. SALA ◽  
PILAR IBARZ ◽  
ALFREDO PALOP ◽  
JAVIER RASO ◽  
SANTIAGO CONDON
Keyword(s):  
Bacillus Subtilis ◽  
Heat Resistance ◽  
High Temperatures ◽  
Phosphate Buffer ◽  
Heating Temperature ◽  
Ph Values ◽  
Z Value ◽  
Acidified Foods ◽  
Citrate Phosphate ◽  
Citrate Phosphate Buffer

The influence of the temperature of sporulation on the heat resistance of Bacillus subtilis in citrate-phosphate buffer of different pH values was investigated. The effect of the pH of the heating menstruum on the heat resistance of spores was strongly influenced by the temperature of sporulation. Spores sporulated at 32°C were at pH 4 much less heat resistant (1/6) than at pH 7. This difference in heat resistance at both pH values was constant regardless of the temperature of treatment. On the contrary, in spores sporulated at 52°C the effect of acid pH on heat resistance was not constant and decreased as heating temperature increased. At 120°C heat resistance was the same at both pH values: z values for pH 7 and 4 were 8.7 and 11.6, respectively. The observed increase of the z value of B. subtilis at pH 4 when sporulated at high temperatures is an added risk that should be taken into account in hot climates, especially when designing sterilization processes at high temperatures for acid/acidified foods.

Properties of spores of Bacillus subtilis with or without a transposon that decreases spore germination and increases spore wet heat resistance

2021 ◽  
Author(s):  
Yannong Luo ◽  
George Korza ◽  
Angela M. DeMarco ◽  
Oscar P. Kuipers ◽  
Yong‐qing Li ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Heat Resistance ◽  
Spore Germination ◽  
Wet Heat

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.

Influence of pH values on electroless Ni-P-SiC plating on AZ91D magnesium alloy

2010 ◽  
Vol 20 ◽  
pp. s674-s678 ◽  
Author(s):  
Yin-ning GOU ◽  
Wei-jiu HUANG ◽  
Rong-chang ZENG ◽  
Yi ZHU
Keyword(s):  
Magnesium Alloy ◽  
Az91d Magnesium Alloy ◽  
Ph Values ◽  
Electroless Ni ◽  
Influence Of Ph

Bacterial Spoilage of Citrus Products at pH Lower than 3.51

1976 ◽  
Vol 39 (12) ◽  
pp. 819-822 ◽  
Author(s):  
B. J. JUVEN
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Thermal Resistance ◽  
Tartaric Acid ◽  
Lactobacillus Brevis ◽  
Acid Inhibition ◽  
Temperature Range ◽  
Ph Values ◽  
Sugar Syrup ◽  
Z Value

A strain of Lactobacillus brevis, L-3, was isolated from a blown can of grapefruit segments in sugar syrup; it caused spoilage of citrus products having pH values lower than 3.5. When inoculated into orange (pH 3.38) and grapefruit (pH 2.99) juices, after 5 h at 30 C L-3 produced 15 and 22 μg diacetyl/ml, respectively, and off-flavor was detectable. L-3 grew in APT broth acidified to pH 3.0 with citric, hydrochloric, phosphoric, or tartaric acid. However, its growth was inhibited at pH 3.6 if the acidulant was lactic acid, while with acetic acid inhibition occurred at a pH between 3.7 and 4.0. The thermal resistance of L-3 in orange serum (pH 3.4) was studied in the temperature range of 52 to 60 C: a z value of 8.3 was obtained. A simple and reliable capillary technique for studying the thermal resistance of gas-producing organisms in liquid foods and media is presented.

scholarly journals The role of pH on the survival of rumen protozoa in steers

2010 ◽  
Vol 39 (10) ◽  
pp. 2262-2267 ◽  
Author(s):  
Raul Franzolin ◽  
Burk A. Dehority
Keyword(s):  
Experimental Period ◽  
Adaptation Period ◽  
Individual Animal ◽  
Effect Of Ph ◽  
Ph Values ◽  
Rumen Protozoa ◽  
Rumen Ph ◽  
Sampling Times ◽  
Ciliate Protozoa

In order to study the effect of pH on defaunation in the rumen, four rumen fistulated steers were fed a basal roughage diet for a 4-week adaptation period followed by 17 weeks of feeding with three diets and two feeding levels of high concentrate diet. Rumen outflow fluid rate was evaluated in both ration levels. Rumen protozoa population was monitored weekly and when animals became defaunated, protozoa were reinoculated with rumen contents from one of the faunated steers. At every two weeks, during all the experimental period, rumen pH was measured in all animals at 0, 4, 8 and 12 h after feeding. It was observed an individual animal influence on the establishment and maintenance of the rumen ciliate protozoa population. In all sampling times, mean rumen pH values were higher in faunated steers than in the defaunated ones. No differences were observed in rumen outflow fluid rates between the two ration levels. Extended periods of low rumen pH are probably more detrimental to the survival of ciliate protozoa in the rumen than other factors.

Heat Resistance of Juice Spoilage Microorganisms

2002 ◽  
Vol 65 (8) ◽  
pp. 1271-1275 ◽  
Author(s):  
ADRIENNE E. H. SHEARER ◽  
ALEJANDRO S. MAZZOTTA ◽  
ROLENDA CHUYATE ◽  
DAVID E. GOMBAS
Keyword(s):  
Heat Resistance ◽  
Process Conditions ◽  
Citrate Buffer ◽  
Ph Values ◽  
Death Time ◽  
High Fructose ◽  
Thermal Death ◽  
Challenge Tests ◽  
D Values ◽  
Thermal Death Time

The heat resistance of various yeasts (Saccharomyces cerevisiae, Rhodotorula mucilaginosa, Torulaspora delbrueckii, and Zygosaccharomyces rouxii), molds (Penicillium citrinum, Penicillium roquefortii, and Aspergillus niger), and lactic acid bacteria (Lactobacillus fermentum and Lactobacillus plantarum) obtained from spoiled acid or acidified food products was determined in 0.1 M citrate buffer at pH values of 3.0, 3.5, and 4.0. S. cerevisiae was the most heat resistant of the microorganisms in citrate buffer, and its heat resistance was further evaluated in apple, grapefruit, calcium-fortified apple, and tomato juices as well as in a juice base with high fructose corn syrup. Decimal reduction times (D-values) and changes in temperature required to change the D-value (z-values) for S. cerevisiae were higher in the juices than in citrate buffer at all pH values tested. The D57°C(135°F)-values varied from 9.4 min in the juice product with pH 2.8 to 32 min in a calcium-added apple juice with pH 3.9. The S. cerevisiae strain used in this study can be used in thermal-death-time experiments in acidic products to calculate process conditions and in challenge tests to validate the calculated temperatures and hold times during processing.

scholarly journals The Influence of pH Values on the Crystallite Size of ZnO by Solvothermal Synthesis

2017 ◽  
Vol 2 (2) ◽  
pp. 118 ◽  
Author(s):  
Ahmadi Jaya Permana ◽  
Dian Wulandari ◽  
Hartati Hartati ◽  
Harsasi Setyawati ◽  
Mochammad Zakki Fahmi
Keyword(s):  
Heat Treatment ◽  
Zinc Oxide ◽  
Crystallite Size ◽  
Solvothermal Synthesis ◽  
Solvothermal Method ◽  
Ph Value ◽  
Semiconductor Material ◽  
X Ray ◽  
Ph Values ◽  
Influence Of Ph

 Zinc oxide (ZnO) is a semiconductor material that widely used in various applications due to its unique properties. Synthesis of ZnO by solvothermal method has been conducted with controlled pH values. The variations of pH value were 10, 11 and 12 by adjusting NaOH content. Crystall structure of the synthesis products after heat treatment at 110oC and 600oC has characterised by X-ray Diffratometer (XRD). Crystallite size of ZnO was measured by Scherrer equation. Crystall phase of ZnO has been observed on all pH value variations at 110 oC with 22,98-37,06 nm of crystallite size, whereas ZnO has been observed on all pH value variations at 600 oC with 41,39-71,77 nm of crystallite size.Keywords: ZnO, pH values, crystallite size, solvothermal

Proteolysis of αs1-casein by chymosin: influence of pH and urea

1977 ◽  
Vol 44 (3) ◽  
pp. 533-540 ◽  
Author(s):  
D. M. Mulvihill ◽  
P. F. Fox
Keyword(s):  
Aqueous Solution ◽  
The State ◽  
Ph Values ◽  
Influence Of Ph ◽  
Hydrolysis Of

SummaryThe specificity of chymosin on αs1-casein was shown to be dependent on the reaction pH and on the state of aggregation of the substrate. In aqueous solution αs1-casein was optimally hydrolysed to αs1-I at pH 5·8; if the casein was solubilized in the isoelectric region by the use of 5 M-urea, optimum proteolysis occurred at pH 2·8. Hydrolysis of αs1-I to yield αs1-II, αs1-III and αs1-IV occurred at pH values > 5·8 in the presence or absence of urea. In the isoelectric region αs1-II, αs1-III and αs1-IV were not formed in the absence of urea where the substrate was aggregated: instead a peptide αs1-V was produced; at the same pH and using urea as a solubilizing agent αs1-II, αs1-III and αs1-IV were formed together with a further peptide αs1-VI.

Effect of pH Values on Magnetic Properties of Electroplated NiFe Layers

2003 ◽  
Vol 437-438 ◽  
pp. 57-60 ◽  
Author(s):  
Xiao Ping Li ◽  
Z.J. Zhao ◽  
S. Ang ◽  
S.J. Koh ◽  
T.B. Oh ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Effect Of Ph ◽  
Ph Values
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