Spore Heat Resistance and Growth Ability at Refrigeration Temperatures of Bacillus spp. and Paenibacillus spp (original) (raw)
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Effects of sporulation media and strain on thermal resistance of Bacillus cereus spores
International Journal of Food Science and Technology, 2007
Spores of Bacillus cereus strains ATCC 7004, ATCC 4342 and ATCC 9818 were produced in four sporulation media (Nutrient Agar supplemented with 1 ppm Mn2+, Fortified Nutrient Agar, Angelotti Medium and Milk Agar) and their percentages of sporulation and heat resistance parameters obtained in a wide temperature range were compared. In all conditions studied, high rates of sporulation were obtained. Clear differences among D-values for spores produced in the four media were observed. the medium which yielded the most resistant spores and the magnitude with which the sporulation medium affected D-values was different for each strain. z-Values of the three strains were not influenced by the medium used to obtain spores.
JDS Communications, 2022
Rework practices used by the dairy industry have the potential to negatively influence product quality; however, this has not been previously investigated. The goal of this study was to use Paenibacillus odorifer, a problematic spore-forming spoilage bacterium, as the target organism to quantify growth rates, thermal resistance, and sporulation during the storage phase of product destined for rework. This study demonstrated the growth potential of P. odorifer during refrigerated storage of chocolate and unflavored milk and the inability for P. odorifer to sporulate in these products within their maximum shelf life and potential use in rework applications. Due to the heat sensitivity of P. odorifer vegetative cells, this study indicates that current rework practices are unlikely to lead to increased milk spoilage associated with this bacterium. Highlights • Paenibacillus odorifer does not sporulate within the shelf life of HTST (high-temperature, short-time) milk. • The microbial quality of reworked milk products is unlikely to be affected by P. odorifer. • We found evidence of a P. odorifer subpopulation surviving 72°C/15 s, but not 80°C/12 min.
Dairy Science & Technology, 2016
The ingredients used for the development and production of milk-based products pose the risk of the introduction of new, emerging spore-formers producing highly thermoresistant spores. Therefore, the aim of this study was to examine the heat resistance of spores isolated from dehydrated ingredients, intermediate and final products. Furthermore, the influence of the heating medium (milk or phosphate buffer) on the heat resistance was determined in order to assess which medium is best to use in the context of dairy processing. Sixteen spore-forming strains from seven different species (Bacillus amyloliquefaciens, Bacillus flexus, Bacillus subtilis, Bacillus thermoamylovorans, Bacillus smithii, Geobacillus pallidus, Geobacillus stearothermophilus) producing thermoresistant spores were selected after their isolation from diverse food products obtained from local dairies such as cocoa powder, milk powder, spices, and dessert products. Spores produced from the chosen strains were tested regarding their heat resistance at 110, 120, and 125°C for 30 min. Highly thermoresistant spores surviving a heat treatment for 30 min at 125°C in milk were produced by B. amyloliquefaciens and G. stearothermophilus. The inactivation of the spores was higher in milk than in phosphate buffer. This study highlights that not only raw milk but also dehydrated ingredients are important sources of thermoresistant spores in dairy processing. Since
Frontiers in Microbiology, 2021
Bacterial spores often survive thermal processing used in the food industry, while heat treatment leads not only to a decrease in the nutritional and organoleptic properties of foods, but also to a delay in fermentation of fermented foods. Selective reduction of undesirable spores without such impediments is an ongoing challenge for food scientists. Thus, increased knowledge of the spore-forming bacteria is required to control them. In this study, the heat resistance results (D100°C) of the spores of four Bacillus species were determined and compared to previous literature, and found that B. cereus has significantly lower heat resistance than the other Bacillus species, B. coagulans, B. subtilis, and B. licheniformis. Using the spores of these strains, this study also evaluated the effects of single and combined supplementation of calcium (0.00–2.00 mM) and manganese (0.00–0.50 mM) on heat resistance (D100°C). The results revealed that the spores of B. licheniformis and B. cereus di...
Spoilage potential of Paenibacillussp. in Brazilian raw milk
Ciência Rural, 2016
ABSTRACT: Bacterial spores are widespread in the environment and can contaminate milk. Spores are resistant to thermal conditions and your germination reduces milk shelf-life because the aerobic bacteria that are sporulated produce proteases and lipases. The aim of this study was identify Paenibacillus sp., the spoilage microbiota, arising from the germination of spores in raw milk and your spoilage potential. Twenty different milk samples were treated at 80°C/12min and plated to isolate spore-forming bacteria. These strains were picked in milk agar and tributyrin agar for verification of their potential proteolytic and lipolytic activities, respectively. Amplification and sequencing of the 16S rRNA gene of the strains for identification by similarity to the DNA sequences deposited in GenBank was performed. One hundred and thirty-seven isolates were obtained, of which 40 (29.2%) showed spoilage activity for milk. Of these, three (7.5%) were identified as strains of Paenibacillus sp....
International Journal of Food Microbiology, 2007
The influence of temperature (10 to 50°C), initial pH (4.0 to 6.0) and sodium chloride concentration (0.5 to 3.0%) on the growth in nutrient broth and in meat extract of Bacillus cereus after mild heat treatment (90°C-10 min) was determined. B. cereus spores survived after heating and they were able to germinate and grow in both media when post-treatment conditions were favourable. Heated B. cereus did not grow at 10 and 50°C or in a medium with pH 4.0. Decreasing pH values and increasing levels of sodium chloride decreased growth rate and increased the lag phase of B. cereus. pH 4.5 was unable to prevent the growth of heated spores in a meat substrate with 0.5% NaCl at 12°C. The combination of pH ≤4.5, NaCl concentration ≥ 1.0% and temperatures ≤12°C was sufficient to inhibit B. cereus growth after heat treatment at 90°C for 10 min, for at least 50 days in nutrient broth and in meat extract. Re-heating at temperatures ≥60°C could control heated B. cereus ATCC 7004 growth.
Influence of pH on heat resistance of spores of Bacillus coagulans in buffer and homogenized foods
International Journal of Food Microbiology, 1999
The influence of pH of heating menstruum (McIlvaine buffer) on the heat resistance of Bacillus coagulans spores has been investigated and compared with the heat resistance in homogenized tomato and asparagus at pH 7 and 4 at a wide range of temperatures. Spores were less heat resistant in all menstrua at acid pH. The magnitude of this effect was greatest at the lowest heating temperatures tested. z values in buffer increased from 8.98C at pH 7 to 10.58C at pH 4. pH of menstrua was the main influencing factor, but media composition also influenced heat resistance: at pH 7 heat resistance was similar in all menstrua (D 5 1.6 min) but at pH 4 the heat resistance in homogenized foods (D 5 0.26 min in tomato and 1118C 1118C