Use of bioluminescence to model the thermal inactivation of Salmonella typhimurium in the presence of a competitive microflora

Duffy, Geraldine; Ellison, Annette; Anderson, Wayne A.; Cole, M.; Stewart, Gordon S. A. B.

doi:10.1128/aem.61.9.3463-3465.1995

Cited by 40 publications

(19 citation statements)

References 15 publications

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“…This is consistent with a number of previous reports that suggested that the composition of the heating medium had a significant influence on the derived D values (Ahmed et al 1995). Factors such as increased fat content and the presence of high levels of competitive flora also had a protective effect against pathogenic microflora during heat treatment (Ahmed et al 1995;Duffy et al 1995). When considering the z values, the effect of propolis on the sensitivity of E. coli O157:H7 to changing temperature in foods was smaller than in broth.…”

Section: Inactivation Of E Coli O157:h7 In Ground Meat By Heat and Psupporting

confidence: 89%

Synergistic Effect of Propolis and Heat Treatment Leading to Increased Injury to Escherichia coli O157:H7 in Ground Pork

Kim

Chung

2014

Journal of Food Safety

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This study was conducted to determine the thermal inactivation of Escherichia coli O157:H7 in the presence of propolis in culture and in ground pork. Overnight cultures (∼106 cfu/mL) or inoculated ground pork (1.0 g, ∼106 cfu/g) were heat treated at 57, 60 and 63 ± 0.1C for predetermined times. The surviving cell populations were enumerated on appropriate media, from which D and z values were determined. The D values for E. coli O157:H7 in broth were 7.33 ± 1.33, 1.34 ± 0.29 and 0.85 ± 0.04 min, respectively (z = 6.4C), whereas in the presence of propolis (8.98 mg/mL), the D values were 0.53 ± 0.02, 0.25 ± 0.00 and 0.17 ± 0.00 min (z = 10.3C). For ground pork, the D values of E. coli O157:H7 were 4.88 ± 0.23, 0.77 ± 0.00 and 0.37 ± 0.00 min, respectively (z = 5.4C), whereas the D values in the presence of propolis (35.92 mg/g) were 2.98 ± 0.02, 0.46 ± 0.03 and 0.26 ± 0.02 min (z = 5.5C). Thermal injury was more pronounced in the presence of propolis at all temperatures. These data suggest that propolis and heat treatment may have a synergistic effect that could have potential applications in the case of meat products. Practical Applications The addition of propolis to Escherichia coli in broth and meat rendered the pathogen more sensitive to the lethal effects of heat at all temperatures, resulting in smaller D values than those obtained with E. coli heat treated alone in both culture and meat samples. These data suggest that propolis and heat treatment may have a synergistic effect that could have potential applications for meat products.

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Section: Inactivation Of E Coli O157:h7 In Ground Meat By Heat and Psupporting

confidence: 89%

Synergistic Effect of Propolis and Heat Treatment Leading to Increased Injury to Escherichia coli O157:H7 in Ground Pork

Kim

Chung

2014

Journal of Food Safety

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“…Bacterial sensitivity to stress is inherent to the species and strain (Patterson 1999). However several factors can influence resistance to an applied stress, such as, the initial number of bacteria; the presence of high concentrations (>8 log CFU ml )1 ) of other microbes (Escherichia coli and Pseudomonas fluorescens) in a test medium has a protective effect on the thermal destruction of Salmonellae (Duffy et al 1995). Similarly the stage of growth can influence resistance with cells in the log phase more susceptible to heat damage and other stresses than cells in the stationary phase Heddleson et al 1991).…”

Section: Introductionmentioning

confidence: 99%

Comparison of 40 Salmonella enterica serovars injured by thermal, high-pressure and irradiation stress

2004

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Aim: To investigate and compare the inherent resistance of 40 Salmonella serovars to heat, irradiation and highpressure stress. Methods and Results: D 10 values for each of the three stresses were calculated for four serovars, chosen as representatives from a catalogue of 40. Based on these results, conditions for each stress were defined, which produced, on average, a three-log reduction in viability. Heat stress (57°C for 13 min), high-pressure stress (350 MPa for 10 min at 20°C) and irradiation stress (1AE5 kGy at 20°C) were applied to all 40 serovars in the collection. Injury and loss of viability for all serovars were determined. Conclusions: Cluster analysis identified five groupings of isolates in terms of resistance to the applied stresses. The independent response of each isolate to all three stresses suggests that there is no relationship between resistances. Significance and Impact of the Study: Each serovar is inherently different. For modelling of real-life food preservation processing the most resistant isolates for that process should be chosen. The results also emphasize the importance of including multiple stress resistant strains when food preservation systems apply multiple stresses.

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“…Such procedures will inevitably lead to overestimation of disinfection. A number of direct observation methodologies have been described that employ vital staining (Wood et al 1998), ATP-levels (Kinniment andWimpenny 1992;Jakubovics and Dow 1997), or reporter genes, such as Lux, for cellular vitality (Walker et al 1992;Duffy et al 1995), but these are labour intensive, generally require that particular reporter constructs are available or are variable in their outcome. Another option is to submerge the test pieces, post-treatment, and to measure the recovery of the surviving cells either by turbidometric (Lambert and van der Ouderaa 1999; or conductimetric (Connolly et al 1994;Johnston and Jones 1995) methods.…”

Section: Introductionmentioning

confidence: 99%

Assessment of resistance towards biocides following the attachment of micro-organisms to, and growth on, surfaces

et al. 2001

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Aims: To develop a rapid method for the assessment of biocidal activity directed towards intact bio®lms. Methods and Results: Escherichia coli and Staphylococcus epidermidis were cultured for up to 48 h within 96-well microtitre plates. The planktonic phase was removed and the wells rinsed. Residual bio®lms were exposed to various concentrations of chloroxylenol, peracetic acid, polyhexamethylene biguanide (PHMB), cetrimide or phenoxyethanol for 1 h. At 15-min intervals, biocide was removed, and the wells washed in neutraliser and ®lled with volumes of fresh medium. Re-growth of the cultures was monitored during incubation at 35°C in the plate reader. Times taken for the treated wells to re-grow to ®xed endpoints were determined and related to numbers of surviving cells. Time±survival curves were constructed and the survival of the attached bacteria, following exposure to the agents for 30 min, interpolated for each biocide concentration. Log±log plots of these survival data and biocide concentration were constructed, and linear regression analysis performed in order to (i) calculate concentration exponents and (ii) compare the effectiveness of the biocides between variously aged bio®lm and planktonic cells. From such analyses iso-effective concentrations of biocide (95% kill in 30 min) were calculated and expressed as planktonic : bio®lm indices (PBI). Conclusions: PBI varied between 1á02 and 0á02, were relatively unaffected by age of the bio®lms but differed signi®cantly between organism and biocide. Notably those compounds with the higher activity against planktonic bacteria (PHMB and peracetic acid) were most prone to a bio®lm effect but remained the most effective of the agents selected. Signi®cance and Impact of the Study: The endpoint method proved robust, enabled the bactericidal effects of the biocides to be assessed against in-situ bio®lms, and was suitable for routine screening applications.

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Use of bioluminescence to model the thermal inactivation of Salmonella typhimurium in the presence of a competitive microflora

Cited by 40 publications

References 15 publications

Synergistic Effect of Propolis and Heat Treatment Leading to Increased Injury to Escherichia coli O157:H7 in Ground Pork

Synergistic Effect of Propolis and Heat Treatment Leading to Increased Injury to Escherichia coli O157:H7 in Ground Pork

Comparison of 40 Salmonella enterica serovars injured by thermal, high-pressure and irradiation stress

Assessment of resistance towards biocides following the attachment of micro-organisms to, and growth on, surfaces

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