Growth Kinetics and Cell Morphology of Listeria monocytogenes Scott A as Affected by Temperature, NaCl, and EDTA†,‡

2003 ◽  
Vol 66 (7) ◽  
pp. 1208-1215 ◽  
Author(s):  
LAURA L. ZAIKA ◽  
JOSEPH S. FANELLI
Keyword(s):  
Listeria Monocytogenes ◽  
Growth Kinetics ◽  
Morphological Characteristics ◽  
Brain Heart Infusion ◽  
Growth Curves ◽  
Stress Conditions ◽  
Plate Count ◽  
Lag Phase ◽  
Kinetics Parameters ◽  
Phase Duration

Growth kinetics and morphological characteristics of Listeria monocytogenes Scott A grown under stress conditions induced by increasing levels of NaCl and EDTA were studied as a function of temperature. L. monocytogenes Scott A was inoculated into brain heart infusion broth (pH 6) at 19, 28, 37, and 42°C. Test cultures contained NaCl (at concentrations of 4.5, 6.0, and 7.5%) or EDTA (at concentrations of 0.1, 0.2, and 0.3 mM); control cultures contained 0.5% NaCl. Growth curves were fitted from plate count data by the Gompertz equation, and growth kinetics parameters were derived. Stationary-phase cells were examined by scanning and transmission electron microscopy. Generation times (GTs) and lag phase duration times (LPDs) increased as additive levels were increased. The bacterium grew at all NaCl levels. At 37 and 42°C, growth was slow in media containing 7.5% NaCl, and no growth occurred in media containing 0.3 mM EDTA. Temperature was a major factor in certain stress conditions that led to cell elongation and loss of flagella. Cells in control media at 28°C grew as short rods (0.5 by 1.0 to 2.0 μm), while at 42°C most cells were 4 to 10 times as long. Higher levels of NaCl at higher temperatures resulted in longer and thicker cells. At 28°C, 0.1 mM EDTA had little effect on growth kinetics and morphology; however, 0.3 mM EDTA caused a sixfold increase in GT and LPD and loss of flagellae, with most cells being two to six times as long as normal. Cell length did not correlate with growth kinetics. The results of this study suggest that the effect of altered morphological characteristics of L. monocytogenes cells grown under stress on the virulence and subsequent survival of these cells should be investigated.

Comparison of Growth Kinetics for Healthy and Heat-Injured Listeria monocytogenes in Eight Enrichment Broths

2002 ◽  
Vol 65 (8) ◽  
pp. 1333-1337 ◽  
Author(s):  
TODD M. SILK ◽  
TATIANA M. T. ROTH ◽  
C. W. DONNELLY
Keyword(s):  
Listeria Monocytogenes ◽  
Growth Curves ◽  
Lag Phase ◽  
Phase Duration ◽  
Enrichment Broth ◽  
Selective Enrichment ◽  
Gompertz Equation ◽  
Selective Agents ◽  
Time Required ◽  
Maximum Population Density

Detection of Listeria in food products is often limited by performance of enrichment media used to support growth of Listeria to detectable levels. In this study, growth curves were generated using healthy and heat-injured Listeria monocytogenes strain F5069 in three nonselective and five selective enrichment broths. Nonselective enrichment media included the current Food and Drug Administration Bacteriological Analytical Manual Listeria enrichment broth base (BAM), Listeria repair broth (LRB), and Trypticase soy broth. Selective enrichment media included BAM with selective agents and LRB with selective agents, BCM L. monocytogenes preenrichment broth, Fraser broth, and UVM-modified Listeria enrichment broth. The Gompertz equation was used to model the growth of L. monocytogenes. Gompertz parameters were used to calculate exponential growth rate, lag-phase duration (LPD), generation time, maximum population density (MPD), and time required for repair of injured cells. Statistical differences (P < 0.05) in broth performance were noted for LPD and MPD when healthy and injured cells were inoculated into the broths. With the exception of Fraser broth, there were no significant differences in the time required for the repair of injured cells. Results indicate that the distinction between selective and nonselective broths in their ability to grow healthy Listeria and to repair sublethally injured cells is not solely an elementary issue of presence or absence of selective agents.

Control of Listeria monocytogenes on Vacuum-Packaged Frankfurters Sprayed with Lactic Acid Alone or in Combination with Sodium Lauryl Sulfate

2008 ◽  
Vol 71 (4) ◽  
pp. 728-734 ◽  
Author(s):  
OLEKSANDR A. BYELASHOV ◽  
PATRICIA A. KENDALL ◽  
KEITH E. BELK ◽  
JOHN A. SCANGA ◽  
JOHN N. SOFOS
Keyword(s):  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Sodium Lauryl Sulfate ◽  
Growth Curves ◽  
Lag Phase ◽  
Lauryl Sulfate ◽  
Phase Duration ◽  
Poultry Products ◽  
All Solutions ◽  
Pathogen Populations

U.S. regulations require that processors employ lethal or inhibitory antimicrobial alternatives in production of ready-toeat meat and poultry products that support growth of Listeria monocytogenes and may be exposed to the processing environment after a lethality treatment. In this study, lactic acid (LA; 5%, vol/vol) and sodium lauryl sulfate (SLS; 0.5%, wt/vol) were evaluated individually or as a mixture (LASLS) for control of L. monocytogenes on frankfurters. Frankfurters were inoculated with a 10-strain mixture of L. monocytogenes, sprayed for 10 s (20 bar, 23 ± 2°C) with antimicrobials or distilled water (DW) before (LASLS or DW) or after (LA, SLS, LASLS, or DW) inoculation (4.8 ± 0.1 log CFU/cm2), vacuum packaged, and stored at 4°C for 90 days. Samples were analyzed for numbers of the pathogen (on PALCAM agar) and for total microbial counts (on tryptic soy agar with yeast extract) during storage. Spraying with DW, LA, or SLS after inoculation reduced numbers of L. monocytogenes by 1.3 ± 0.2, 1.8 ± 0.5, and 2.0 ± 0.4 log CFU/cm2, respectively. The LASLS mixture applied before or after inoculation reduced pathogen populations by 1.8 ± 0.4 and 2.8 ± 0.2 log CFU/cm2, respectively. No further reduction by any treatment was observed during storage. The bacterial growth curves (fitted by the model of Baranyi and Roberts) indicated that the lag-phase duration of the bacterium on control samples (13.85 to 15.18 days) was extended by spraying with all solutions containing LA. For example, LA suppressed growth of L. monocytogenes for 39.14 to 41.01 days. Pathogen growth rates also were lower on frankfurters sprayed after inoculation with LA or LASLS compared to those sprayed with DW. Therefore, spraying frankfurters with a mixture of LA and SLS may be a useful antilisterial alternative treatment for ready-to-eat meat and poultry products.

Effect of Sodium Nitrite on Growth of Shigella flexneri

1991 ◽  
Vol 54 (6) ◽  
pp. 424-428 ◽  
Author(s):  
LAURA L. ZAIKA ◽  
ANNA H. KIM ◽  
LOUISE FORD
Keyword(s):  
Exponential Growth ◽  
Shigella Flexneri ◽  
Salt Content ◽  
Brain Heart Infusion ◽  
Growth Curves ◽  
Inhibitory Effect ◽  
Plate Count ◽  
Generation Times ◽  
High Salt Content ◽  
Lag Times

A partial factorial design study of the effect of NaNO2 (0, 100, 200, 1000 ppm) in combination with NaCl (0.5, 2.5, 4.0%), pH (7.5, 6.5, 5.5), and temperature (37, 28, 19°C) on growth of Shigella flexneri is reported. Experiments were done aerobically in brain-heart infusion medium, using an inoculum of 1 × 103 CFU/ml. Growth curves were fitted from plate count data by the Gompertz equation; exponential growth rates, lag times, generation times, and maximum populations were derived for all variable combinations. In the absence of nitrite, the organism grew well under all test conditions at 37 and 28°C but did not grow at 19°C at pH 5.5 nor at pH 7.5 with 4% NaCl. Nitrite did not affect growth in media of pH 7.5 at 37 and 28°C. At pH 6.5 growth was inhibited by 1000 ppm NaNO2. The organism failed to grow at 19°C at all nitrite levels in the presence of 2.5 or 4.0% NaCl. The inhibitory effect of nitrite was much greater in media of pH 5.5 and increased with increasing salt levels. More inhibition was apparent at 28 than at 37°C. While lack of growth was used as a paradigm of the effect of nitrite on S. flexneri, nitrite also increased the lag and generation times and decreased the exponential growth rate. Results indicated that NaNO2 in combinations with low temperature, low pH, and high salt content can effectively inhibit the growth of S. flexneri.

scholarly journals Growth of Listeria monocytogenes in Thawed Frozen Foods

2017 ◽  
Vol 80 (3) ◽  
pp. 447-453 ◽  
Author(s):  
Ai Kataoka ◽  
Hua Wang ◽  
Philip H. Elliott ◽  
Richard C. Whiting ◽  
Melinda M. Hayman
Keyword(s):  
Growth Rate ◽  
Listeria Monocytogenes ◽  
Growth Rates ◽  
Storage Temperature ◽  
Growth Parameters ◽  
Quadratic Model ◽  
Lag Phase ◽  
Frozen Foods ◽  
Phase Duration ◽  
Primary Model

ABSTRACT The growth characteristics of Listeria monocytogenes inoculated onto frozen foods (corn, green peas, crabmeat, and shrimp) and thawed by being stored at 4, 8, 12, and 20°C were investigated. The growth parameters, lag-phase duration (LPD) and exponential growth rate (EGR), were determined by using a two-phase linear growth model as a primary model and a square root model for EGR and a quadratic model for LPD as secondary models, based on the growth data. The EGR model predictions were compared with growth rates obtained from the USDA Pathogen Modeling Program, calculated with similar pH, salt percentage, and NaNO2 parameters, at all storage temperatures. The results showed that L. monocytogenes grew well in all food types, with the growth rate increasing with storage temperature. Predicted EGRs for all food types demonstrated the significance of storage temperature and similar growth rates among four food types. The predicted EGRs showed slightly slower rate compared with the values from the U.S. Department of Agriculture Pathogen Modeling Program. LPD could not be accurately predicted, possibly because there were not enough sampling points. These data established by using real food samples demonstrated that L. monocytogenes can initiate growth without a prolonged lag phase even at refrigeration temperature (4°C), and the predictive models derived from this study can be useful for developing proper handling guidelines for thawed frozen foods during production and storage.

Model for Aerobic Growth of Shigella flexneri Under Various Conditions of Temperature, pH, Sodium Chloride and Sodium Nitrite Concentrations

1992 ◽  
Vol 55 (7) ◽  
pp. 509-513 ◽  
Author(s):  
LAURA L. ZAIKA ◽  
JOHN G. PHILLIPS ◽  
ROBERT L. BUCHANAN
Keyword(s):  
Sodium Chloride ◽  
Growth Kinetics ◽  
Sodium Nitrite ◽  
Shigella Flexneri ◽  
Brain Heart Infusion ◽  
Growth Curves ◽  
Quadratic Model ◽  
Aerobic Growth ◽  
Gompertz Equation ◽  
Kinetics Of

A modified factorial design was used to measure the effects and interactions of temperature (10 to 37°C), pH (5.5 to 7.5), sodium chloride (0.5 to 5.0%), and sodium nitrite (0 to 1000 ppm) on the aerobic growth kinetics of Shigella flexneri in brain heart infusion broth. A total of 592 cultures were analyzed, with growth curves being generated using the Gompertz equation. A quadratic model for growth of S. flexneri in terms of temperature, pH, sodium chloride, and sodium nitrite concentrations was obtained by response surface analysis. This model provides an estimate of bacterial growth in response to any combination of the variables studied within the specified ranges. Estimates obtained with the model compared favorably with growth of S. flexneri in milk.

The Combination of Lactate and Diacetate Synergistically Reduces Cold Growth in Brain Heart Infusion Broth across Listeria monocytogenes Lineages

2010 ◽  
Vol 73 (4) ◽  
pp. 631-640 ◽  
Author(s):  
MATTHEW J. STASIEWICZ ◽  
MARTIN WIEDMANN ◽  
TERESA M. BERGHOLZ
Keyword(s):  
Listeria Monocytogenes ◽  
Synergistic Effects ◽  
Brain Heart Infusion ◽  
Growth Parameter ◽  
Lag Phase ◽  
Minor Effect ◽  
Growth Inhibitors ◽  
Acid Growth ◽  
Potassium Lactate ◽  
Sodium Diacetate

Combinations of organic acids are often used in ready-to-eat foods to control the growth of Listeria monocytogenes during refrigerated storage. The purpose of this study was to quantitatively assess synergy between two organic acid growth inhibitors under conditions similar to those present in cold-smoked salmon, and to assess the effect of evolutionary lineage on response to those growth inhibitors. Thirteen strains of L. monocytogenes, representing lineages I and II, were grown at 7°C in broth at pH 6.1 and 4.65% water-phase NaCl, which was supplemented with 2% potassium lactate, 0.14% sodium diacetate, or the combination of both at the same levels. Our data suggest that lineages adapt similarly to these inhibitors, as the only significant growth parameter difference between lineages was a minor effect (± 0.16 day, P = 0.0499) on lag phase (λ). For all strains, lactate significantly extended λ, from 2.6 ± 0.4 to 3.8 ± 0.5 days (P < 0.001), and lowered the maximum growth rate (μmax) from 0.54 ± 0.06 to 0.49 ± 0.04 log(CFU/ml)/day (P < 0.001), compared with the control. Diacetate was ineffective alone, but in combination with lactate, synergistically increased λ to 6.6 ± 1.6 days (P < 0.001) and decreased μmax to 0.34 ± 0.05 log(CFU/ml)/day (P < 0.001). Monte Carlo simulations provided further evidence for synergy between diacetate and lactate by predicting signficantly slower growth to nominal endpoints for the combination of inhibitors. This study shows potassium lactate and sodium diacetate have significant synergistic effects on both λ and μmax of L. monocytogenes at refrigeration temperature in broth, and justifies combining these inhibitors, at effective levels, in food product formulations.

A Predictive Model for the Growth of Listeria monocytogenes in Commercial Blue Crab (Callinectes sapidus)

2017 ◽  
Vol 80 (11) ◽  
pp. 1872-1876
Author(s):  
Salina Parveen ◽  
Channel White ◽  
Mark L. Tamplin
Keyword(s):  
Listeria Monocytogenes ◽  
Blue Crab ◽  
Callinectes Sapidus ◽  
Lag Phase ◽  
Published Data ◽  
Predictive Tool ◽  
Phase Duration ◽  
Primary Model ◽  
Increasing Temperature ◽  
Crab Meat

ABSTRACT During the processing and handling of commercial blue crab (Callinectes sapidus), Listeria monocytogenes can potentially contaminate cooked meat and grow to hazardous levels. To manage this risk, predictive models are useful tools for designing and implementing preventive controls; however, no model specific for blue crab meat has been published or evaluated. In this study, a cocktail of L. monocytogenes strains was added to pasteurized blue crab meat, which was incubated at storage temperatures from 0 to 35°C. At selected time intervals, L. monocytogenes was enumerated by direct plating onto modified Oxford agar. A primary model was fitted to kinetic data to estimate the lag-phase duration (LPD) and growth rate (GR). Listeria monocytogenes replicated from 0 to 35°C, with GR ranging from 0.004 to 0.518 log CFU/h. Overall, the LPD decreased with increasing temperature, displaying a maximum value of 187 h at 0°C; however, this trend was not consistent. The LPD was not detected at 10°C, and it occurred inconsistently from trial to trial. A secondary GR model (R2 = 0.9892) for pasteurized crab meat was compared with the L. monocytogenes GR in fresh crab meat, demonstrating bias and accuracy factors of 0.98 and 1.36, respectively. The model estimates varied from other published data and models, especially at temperatures ≥5°C, supporting the need for a specific predictive tool for temperature deviations.

scholarly journals Single Mathematical Parameter for Evaluation of the Microorganisms’ Growth as the Objective Function in the Optimization by the DOE Techniques

2020 ◽  
Vol 8 (11) ◽  
pp. 1706
Author(s):  
Maciej Konopacki ◽  
Adrian Augustyniak ◽  
Bartłomiej Grygorcewicz ◽  
Barbara Dołęgowska ◽  
Marian Kordas ◽  
...  
Keyword(s):  
Objective Function ◽  
Growth Parameter ◽  
Growth Curves ◽  
Culture Conditions ◽  
Lag Phase ◽  
Mathematical Approach ◽  
Phase Duration ◽  
Scientific Disciplines ◽  
Shape Curve ◽  
Model Curve

The cultivation of bacteria sets a ground for studying biological processes in many scientific disciplines. The development of the bacterial population is commonly described with three factors that can be used to evaluate culture conditions. However, selecting only one of them for the optimization protocol is rather problematic and may lead to unintended errors. Therefore, we proposed a novel mathematical approach to obtain a single factor that could be used as the objective function to evaluate the whole growth dynamic and support the optimization of the biomass production process. The sigmoidal-shape curve, which is the commonly used function to plot the amount of biomass versus time, was the base for the mathematical analysis. The key process parameters, such as maximal specific growth rate and lag-phase duration were established with the use of mathematical coefficients of the model curve and combined to create the single growth parameter. Moreover, this parameter was used for the exemplary optimization of the cultivation conditions of Klebsiella pneumoniae that was cultured to be further used in the production of lytic bacteriophages. The proposed growth parameter was successfully validated and used to calculate the optimal process temperature of the selected bacterial strain. The obtained results indicated that the proposed mathematical approach could be effortlessly adapted for a precise evaluation of growth curves.

Bacillus cereus: Aerobic Growth Kinetics

1993 ◽  
Vol 56 (3) ◽  
pp. 211-214 ◽  
Author(s):  
ROBERT C. BENEDICT ◽  
TIMOTHY PARTRIDGE ◽  
DONNA WELLS ◽  
ROBERT L. BUCHANAN
Keyword(s):  
Sodium Chloride ◽  
Bacillus Cereus ◽  
Sodium Nitrite ◽  
Variable Temperature ◽  
Brain Heart Infusion ◽  
Growth Curves ◽  
Food Storage ◽  
Lag Phase ◽  
Generation Times ◽  
Plate Counts

Three strains of Bacillus cereus were cultured in brain heart infusion medium aerobically under conditions of variable temperature (5 to 42°C), sodium chloride concentrations (0.5–5%), pH (4.5 - 7.5), and sodium nitrite concentration (0 mg/L - 200 mg/L) to simulate conditions of normal and adverse food storage. Cultures were sampled at selected times, and plate counts were used to calculate growth curves under each condition. None of the three strains grew at 5°C, but growth did occur slowly at 8°C, and was most rapid at a temperature of 37°C. Growth occurred in media without additives in all pH's examined between 8 and 42°C. Decreasing the pH and increasing levels of sodium chloride and sodium nitrite increased the lag phase and generation times of the organism.

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