Sporulation and Heat Resistance of Psychrophilic Strains of Bacillus

Shehata, T. E.; Collins, E. B.

doi:10.3168/jds.s0022-0302(72)85684-4

Cited by 42 publications

(18 citation statements)

References 6 publications

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“…A study by Shehata and Collins (1972) found that 36% of raw milk samples contained psychrotrophic Bacillus spp.…”

Section: Resultsmentioning

confidence: 99%

“…First, it has a very neutral pH (approximately 6.8), which will not inhibit germination or cell growth (Miller and others 2007 Pasteurized milk typically contains species of Streptococcus, Lactobacillus, and Bacillus. In fact, Shehata and Collins (1972) found that as much as 36% of raw milk samples in one study contained psychrotrophic Bacillus spp. Milk has also been linked to the foodborne pathogens that cause human illnesses such as campylobacteriosis, salmonellosis, listeriosis, Q fever, and hemorrhagic colitis.…”

Section: Milk As a Food For Intentional Contaminationmentioning

confidence: 99%

“…The diarrheal syndrome is associated with meat and dairy products while the emetic toxin is linked to starchy products such as cereals and rice (Jay and others 2005). In fact, Shehata and Collins (1972) found that as much as 36% of raw milk samples in one study contained psychrotrophic…”

Section: Introductionmentioning

confidence: 99%

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Comparing the Mannitol-Egg Yolk-Polymyxin Agar Plating Method with the Three-Tube Most-Probable-Number Method for Enumeration of Bacillus cereus Spores in Raw and High-Temperature, Short-Time Pasteurized Milk

Harper

Getty

Schmidt

et al. 2011

Journal of Food Protection

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The Food and Drug Administration's Bacteriological Analytical Manual recommends two enumeration methods for Bacillus spp.: 1) standard plating method using mannitol-egg yolkpolymyxin (MYP) agar and 2) most probable number (MPN) method with tryptic soy broth supplemented with 0.1% polymyxin sulfate. Preliminary research evaluated three inoculum preparation methods using EZ-Spore™ B. cereus pellets. Two methods involved EZ-Spore™ B.cereus pellets that were dissolved in deionized (DI) water, grown in brain heart infusion broth with manganese sulfate, and then heated to produce spores. The third inoculum preparation method of dissolving EZ-Spore™ pellets only in DI water was the most efficient due to 100% spores being present in the inoculum. Preliminary research also determined that MPN method recovered greater (p<0.05) B. cereus populations than MYP method in inoculated ultra-high temperature pasteurized skim and 2% milk. The objective of the main study was to compare the MYP and MPN method for detection and enumeration of B. cereus in raw and high-temperatureshort-time pasteurized skim, 2%, and whole milk at 4 °C for 96 h. Milk samples were inoculated with B. cereus EZ-Spores™ dissolved in DI water and sampled at 0, 48, and 96 h after inoculation. No differences (p>0.05) were observed among sampling times so data was pooled for overall mean values for each treatment. The overall B. cereus population mean of pooled sampling times for MPN method (2.59 log CFU/mL) was greater (p<0.05) than MYP plating method (1.89 log CFU/mL). B. cereus populations ranged from 3.40 log CFU/mL to 2.40 log CFU/mL for inoculated milk treatments for MYP and MPN methods, which is well below the necessary level for toxin production. Even though MPN method enumerated more B. cereus, the MYP method should be used by industry for enumeration of B. cereus due to its ease of use and rapid turnover time (2 d compared to 5 d with MPN). However, MPN method should be used for validation research due to its greater populations recovered. EZ-Spore™ B. cereus pellets were found to be an acceptable spore inoculum for validation research because the inoculum consists of 100% spores and does not contain vegetative cells.

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“…A study by Shehata and Collins (1972) found that 36% of raw milk samples contained psychrotrophic Bacillus spp.…”

Section: Resultsmentioning

confidence: 99%

Section: Milk As a Food For Intentional Contaminationmentioning

confidence: 99%

See 1 more Smart Citation

Comparing the Mannitol-Egg Yolk-Polymyxin Agar Plating Method with the Three-Tube Most-Probable-Number Method for Enumeration of Bacillus cereus Spores in Raw and High-Temperature, Short-Time Pasteurized Milk

Harper

Getty

Schmidt

et al. 2011

Journal of Food Protection

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“…1983; Dufrenne et al . 1995) and 5C (Shehata and Collins 1971). Moreover, B. cereus was found to grow well in noodles stored at 5C in the present study, which further indicates that this organism is a psychrotroph.…”

Section: Resultsmentioning

confidence: 99%

TEMPERATURE DEPENDENT GROWTH CHARACTERISTICS AND A PREDICTIVE MATHEMATICAL MODEL OF BACILLUS CEREUS IN WET NOODLES

Lee

Kim

et al. 2011

Journal of Food Safety

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We examined the growth characteristics and developed a mathematical model to predict the growth kinetics of Bacillus cereus in fresh wet noodles. Noodles were incubated with B. cereus at 5, 10, 20 and 30C. The primary model that we developed to obtain the specific growth rate (SGR) and lag time (LT) fit well (r2 = 0.9621–0.9977) with the Gompertz equation. The SGR of B. cereus increased with increasing temperature. A secondary polynomial model was obtained by SAS regression analysis and calculated as: SGR = −0.0128 + 0.00229*T + 0.0003*T2. The appropriateness of this secondary polynomial model was verified by the mean square error (MSE = 0.0001 for SGR model), bias factor (Bf = 0.9012 for SGR model), accuracy factor (Af = 1.3333 for SGR model) and coefficient of determination (r2 = 0.9955 for SGR). This secondary polynomial model is therefore in good agreement with the validation calculations and may be used as a practical predictive model for the growth of B. cereus in wet noodles as a function of storage temperature. PRACTICAL APPLICATIONS Wet noodles carry a potential risk of food poisoning by B. cereus. The predictive model developed here can increase confidence and improve the shelf life and safety of foods. Moreover, the results obtained using the predicted model developed here were in good agreement with the observed values. Therefore, the developed model may be used as a practical predictive model for the growth of B. cereus in wet noodles as a function of storage temperature.

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“…Suspensions of spores in distilled water were obtained following the technique proposed by Shehata and Collins [40]. A Roux bottle containing a sporulation medium, which consisted of nutritive agar (Britania Laboratories) with 0.05% MnSO 4 and 0.05% MgSO 4 , was inoculated and incubated at 30 • C during a 7-10-day period.…”

Section: Spores Formation and Collectionmentioning

confidence: 99%

Effect of the radiation flux on the photocatalytic inactivation of spores of Bacillus subtilis

Zacarías

Vaccari

Alfano

et al. 2010

Journal of Photochemistry and Photobiology A: Chemistry

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a b s t r a c tIn this paper, the photocatalytic inactivation of dry spores of Bacillus subtilis dispersed on TiO 2 films and irradiated with UV-A radiation (2.44-0.29 mW cm −2 ) was studied. Experimental results indicate a minor reduction in the number of viable spores (69% of inactivation after 48 h of irradiation) when they were irradiated with UV-A radiation on borosilicate glass plates (without TiO 2 ), confirming the resistance of spores to UV-A radiation. However, the number of viable spores significantly decreased when they were irradiated with UV-A under similar conditions but on plates coated with TiO 2 (99.88% of inactivation after 24 h of irradiation), showing that dry spores of B. subtilis are vulnerable to photocatalytic inactivation. A simplified scheme was proposed to model the photocatalytic inactivation of B. subtilis, from which a kinetic expression was derived. Since the rate of photocatalytic inactivation is strongly dependent on the flux of the UV radiation on the TiO 2 films, the radiation field was modeled by means of CFD software. Experimental results of spore inactivation were fitted with the derived kinetic expression, showing the inactivation rate has a square root dependence on the radiation flux reaching the photocatalyst film.

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Sporulation and Heat Resistance of Psychrophilic Strains of Bacillus

Cited by 42 publications

References 6 publications

Comparing the Mannitol-Egg Yolk-Polymyxin Agar Plating Method with the Three-Tube Most-Probable-Number Method for Enumeration of Bacillus cereus Spores in Raw and High-Temperature, Short-Time Pasteurized Milk

Comparing the Mannitol-Egg Yolk-Polymyxin Agar Plating Method with the Three-Tube Most-Probable-Number Method for Enumeration of Bacillus cereus Spores in Raw and High-Temperature, Short-Time Pasteurized Milk

TEMPERATURE DEPENDENT GROWTH CHARACTERISTICS AND A PREDICTIVE MATHEMATICAL MODEL OF BACILLUS CEREUS IN WET NOODLES

Effect of the radiation flux on the photocatalytic inactivation of spores of Bacillus subtilis

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