scholarly journals Characterisation of Lactobacillus rhamnosus VT1 and its effect on the growth of Candida maltosa YP1

2008 ◽  
Vol 25 (No. 5) ◽  
pp. 272-282 ◽  
Author(s):  
D. Liptáková ◽  
Ľ. Valík ◽  
A. Lauková ◽  
V. Strompfová
Keyword(s):  
Growth Rate ◽  
Incubation Temperature ◽  
Lactobacillus Rhamnosus ◽  
Microbial Interactions ◽  
Lag Phase ◽  
Regression Equations ◽  
Candida Maltosa ◽  
Food Protection ◽  
Spoilage Yeast ◽  
Standard Response

The combined effect of initial amount of 18 h <i>L. rhamnosus</i> VT1 inoculum and incubation temperature on the growth of <i>Candida maltosa</i> YP1, an oxidative food spoilage yeast strain, was primarily modelled and studied by standard response surface methodology. This study resulted in the following linear regression equations characterising lag time and growth rate of <i>C. maltosa</i> YP1 in milk in competition with the potentially protective lactobacillus strain. Lag-phase of <i>C. maltosa</i> was strongly influenced by the amount of lactobacillus inoculum (<i>V</i><sub>0</sub>) and incubation temperature (1/<i>T</i>). The synergic effect of both these factors was also evident as results from the equation lag = –33.50 + 186.38 × <i>V</i><sub>0</sub> × 1/<i>T</i> + 512.27 × 1/<i>T</i> – 5.511 × <i>V</i><sub>0</sub> (<i>R</i><sup>2</sup><sub>(λ)</sub> = 0.849). The growth rate was sufficiently described by the linear relation: <i>Gr</i><sub>Cm</sub> = –0.00046 + 0.0033 × <i>T</i> – 0.0016 × <i>V</i><sub>0 (<i>R</i><sup>2</sup><sub>(Gr)</sub> = 0.847). On the basis of these equations, the mutual microbial interactions and the potential application of the lactobacillus strains to food protection are discussed.

scholarly journals Growth characterisation of Staphylococcus aureus in milk: a quantitative approach

2009 ◽  
Vol 27 (No. 6) ◽  
pp. 433-453 ◽  
Author(s):  
A. Medveďová ◽  
Ľ. Valík ◽  
Z. Sirotná ◽  
D. Liptáková
Keyword(s):  
Staphylococcus Aureus ◽  
Growth Rate ◽  
Incubation Temperature ◽  
Food Poisoning ◽  
Raw Milk ◽  
Lag Phase ◽  
Phase Duration ◽  
Temperature Range ◽  
Root Model ◽  
Toxigenic Strains

<i>Staphylococcus aureus</i> is a pathogenic bacterium that induces several of human illnesses. The staphylococcal enterotoxin (SE) production as the results of previous growth of toxigenic strains is the most crucial problem which may lead to the staphylococcal food poisoning outbreaks in humans. That is why the growth of three strains of <i>Staphylococcus aureus</i> was characterised in milk and modelled in dependence of temperature. For the lag phase duration of <i>S. aureus</i> 2064, the Davey model was used with the following result: ln(1/lag) = 1.973 – 87.92/<i>T</i> + 285.09/<i>T</i><sup>2</sup> (<i>R</i><sup>2</sup> = 0.962). The dependence of the growth rate on incubation temperature was modelled by the Ratkowsky square root model and Gibson in sub-optimal and whole temperature range, respectively. The validation of both models showed high significance of the growth rate data fitting. The optimal temperature of <i>T</i><sub>opt</sub> = 38.5°C was resulted from Gibson model for the <i>S. aureus</i> 2064 growth in milk. For practical purpose, the time necessary for the increase of <i>S. aureus</i> by 3 log counts was also calculated within the growth temperature range. These data may provide useful information e.g. for the producers using raw milk in their artisanal cheese practice as the specific strains were used in this study.

scholarly journals Effect of lactic acid on the growth dynamics of Candida maltosa YP1

2011 ◽  
Vol 21 (No. 2) ◽  
pp. 43-49 ◽  
Author(s):  
D. Lauková ◽  
Ľ. Valík ◽  
F. Görner
Keyword(s):  
Growth Rate ◽  
Lactic Acid ◽  
Specific Growth Rate ◽  
Acid Concentration ◽  
Specific Growth ◽  
Glucose Solution ◽  
Growth Dynamics ◽  
Lag Phase ◽  
Lactic Acid Concentration ◽  
Candida Maltosa

The growth dynamics of the oxidative imperfect yeast strain Candida maltosa YP1 isolated from the surface of fruit yoghurt was studied in relation to the lactic acid concentration ranging from 0 to 1.6% (w/v). The maximal specific growth rate of 0.36 h<sup>&ndash;1</sup> and minimal lag-phase duration of 2.9 h were found in the glucose solution without lactic acid at 25&deg;C. The decrease of the natural logarithm of both the specific growth rate (ln &micro;) and the lag-phase prolongation (ln ) in the dependence on the increase of lactic acid concentration (0&ndash;1.59%) was significantly linear (ln&nbsp;&micro; = &ndash;1.1458 &ndash; 0.6056 c; R<sup>2</sup><sub>(&micro;) </sub>= 0.9526; ln l = 1.0141 + 1.9766 c; R<sup>2</sup><sub>() </sub>= 0.9577). Based on these equations, the prediction of the time necessary for C. maltosa YP1 to reach 1 &times; 10<sup>6</sup> CFU/ml in the dependance on lactic acid concentration and, the initial density of the yeast culture was calculated. For example, C. maltosa YP1 was able to reach the level of 1 &times; 10<sup>6</sup> CFU/ml in a model glucose solution at the initial concentration N<sub>0</sub> = 1 CFU/ml, 0.9% lactic acid and 25&deg;C within 2 d. The growth predictions presented indicate a considerable resistance of C. maltosa YP1 to lactic acid in the concentration of up to 1.3% (w/v). &nbsp;

Effect of Carbon Dioxide on the Growth of Pseudomonas fluorescens and Listeria monocytogenes in Aerobic Atmospheres

1997 ◽  
Vol 60 (12) ◽  
pp. 1548-1552 ◽  
Author(s):  
M. T. HENDRICKS ◽  
J. H. HOTCHKISS
Keyword(s):  
Carbon Dioxide ◽  
Growth Rate ◽  
Listeria Monocytogenes ◽  
Pseudomonas Fluorescens ◽  
Growth Curves ◽  
Co2 Concentration ◽  
Lag Phase ◽  
Regression Equations ◽  
Regression Analyses ◽  
Co2 Levels

The effects of atmospheres containing 20% O2 and 0 to 80% CO2 or 30% CO2 and 0 to 40% O2 (balance N2) on the growth rate and lag phase of Listeria monocytogenes and Pseudomonas fluorescens in buffered nutrient broth at 7.5°C were investigated. Increasing CO2 concentration lengthened the lag phase and decreased the growth rate of both organisms. CO2 levels above 20% significantly reduced the growth rate of P. fluorescens and CO2 levels of 80% significantly reduced the growth rate of L. monocytogenes. Linear and multiple regression analyses were used to describe L. monocytogenes and P. fluorescens growth curves. The R2 values of all regression analyses were greater than 93%. The regression equations indicate that CO2 inhibits the growth of both P. fluorescens and L. monocytogenes even in the presence of 20% O2, However, the effect of CO2 on P.fluorescens is greater than on L. monocytogenes.

Alaskan moose measurements and weights and measurement–weight relationships

1978 ◽  
Vol 56 (2) ◽  
pp. 298-306 ◽  
Author(s):  
Albert W. Franzmann ◽  
Robert E. LeResche ◽  
Robert A. Rausch ◽  
John L. Oldemeyer
Keyword(s):  
Growth Rate ◽  
Blood Parameters ◽  
Field Application ◽  
Regression Equations ◽  
Body Measurements ◽  
Male And Female ◽  
Total Length ◽  
Chest Girth ◽  
Hind Foot ◽  
Alces Alces Gigas

A total of 1329 Alaskan moose (Alces alces gigas) were measured for total length, 1340 for chest girth, 1317 for hind foot, 618 for shoulder height, and 1219 for ear length. Five hundred and four moose were weighed. These data were classified by sex, age, month sampled, and location. Growth rates were plotted and discussed. No morphometric differences were detected by sex and location classifications up to age 36 months. Location differences were detected which corresponded to general condition, productivity, and condition related blood parameters of the populations. Seasonal weight patterns demonstrated increases from 21 to 55% from spring to late fall. Measurements, particularly total lengths, were better indicators of growth rate than were weights. All body measurements were significantly correlated with weight: total length, r (correlation coefficient) = 0.94; chest girth, r = 0.90; shoulder height, r = 0.87; and hind foot, r = 0.81. Combined sex regression equations were derived because the slight differences between the male and female regression lines were unimportant in field application. These regression equations were as follows: weight (kilograms) = −239.7 + 2.07(total length); weight (kilograms) = −245.3 + 3.14(chest girth).

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.

The effect of level of environment on sex differences in pre-weaning growth rate in beef cattle

1977 ◽  
Vol 25 (1) ◽  
pp. 47-51 ◽  
Author(s):  
I. R. Hopkins
Keyword(s):  
Growth Rate ◽  
Sex Differences ◽  
Beef Cattle ◽  
Growth Rates ◽  
Additive Models ◽  
Regression Equations ◽  
Male And Female ◽  
Breed Differences ◽  
Per Se ◽  
Simple Regression

SUMMARYUsing pre-weaning records of 3822 calves from 11 Victorian herds, mean male and female growth rates and corresponding sex differences were calculated for each dam age and herd-year class. From these means simple regression equations relating sex differences and growth rates were calculated. There was a close similarity between equations based on dam age means and those based on herd-year means while correlations between sex differences and male growth rates were high.These results showed that sex differences and female growth rates could be predicted reliably from the level of environment as measured by male growth rate. Sex differences predicted by these regression relationships differed markedly from those predicted by the simple multiplicative and simple additive models generally used in adjusting for sex differences in selection.The results also suggested that other differences such as breed differences may be predictable in the same way and that such differences are determined primarily by the level of environment per se rather than differences in the nature of the components contributing to that level.

scholarly journals Quantitative Interaction Effects of Carbon Dioxide, Sodium Chloride, and Sodium Nitrite on Neurotoxin Gene Expression in Nonproteolytic Clostridium botulinum Type B

2004 ◽  
Vol 70 (5) ◽  
pp. 2928-2934 ◽  
Author(s):  
Maria Lövenklev ◽  
Ingrid Artin ◽  
Oskar Hagberg ◽  
Elisabeth Borch ◽  
Elisabet Holst ◽  
...  
Keyword(s):  
Gene Expression ◽  
Carbon Dioxide ◽  
Growth Rate ◽  
Sodium Chloride ◽  
Optical Density ◽  
Sodium Nitrite ◽  
Clostridium Botulinum ◽  
Lag Phase ◽  
Type B ◽  
Phase Duration

ABSTRACT The effects of carbon dioxide, sodium chloride, and sodium nitrite on type B botulinum neurotoxin (BoNT/B) gene (cntB) expression in nonproteolytic Clostridium botulinum were investigated in a tryptone-peptone-yeast extract (TPY) medium. Various concentrations of these selected food preservatives were studied by using a complete factorial design in order to quantitatively study interaction effects, as well as main effects, on the following responses: lag phase duration (LPD), growth rate, relative cntB expression, and extracellular BoNT/B production. Multiple linear regression was used to set up six statistical models to quantify and predict these responses. All combinations of NaCl and NaNO2 in the growth medium resulted in a prolonged lag phase duration and in a reduction in the specific growth rate. In contrast, the relative BoNT/B gene expression was unchanged, as determined by the cntB-specific quantitative reverse transcription-PCR method. This was confirmed when we measured the extracellular BoNT/B concentration by an enzyme-linked immunosorbent assay. CO2 was found to have a major effect on gene expression when the cntB mRNA levels were monitored in the mid-exponential, late exponential, and late stationary growth phases. The expression of cntB relative to the expression of the 16S rRNA gene was stimulated by an elevated CO2 concentration; the cntB mRNA level was fivefold greater in a 70% CO2 atmosphere than in a 10% CO2 atmosphere. These findings were also confirmed when we analyzed the extracellular BoNT/B concentration; we found that the concentrations were 27 ng · ml−1 · unit of optical density−1 in the 10% CO2 atmosphere and 126 ng · ml−1 · unit of optical density−1 in the 70% CO2 atmosphere.

Evaluation of temperature effect on growth rate of Lactobacillus rhamnosus GG in milk using secondary models

2013 ◽  
Vol 67 (7) ◽  
Author(s):  
Ľubomír Valík ◽  
Alžbeta Medveďová ◽  
Michal Čižniar ◽  
Denisa Liptáková
Keyword(s):  
Growth Rate ◽  
Growth Parameters ◽  
Lactobacillus Rhamnosus ◽  
Probiotic Bacterium ◽  
Extended Model ◽  
Temperature Model ◽  
Lactobacillus Rhamnosus Gg ◽  
Model Application ◽  
Cardinal Temperature ◽  
Cardinal Temperatures

AbstractThe application of secondary temperature models on growth rates of Lactobacillus rhamnosus GG, the much studied probiotic bacterium, is investigated. Growth parameters resulting from a primary fitting were modelled against temperature using the following models: Hinshelwood model (H), Ratkowsky extended model (RTK2), Zwietering model (ZWT), and cardinal temperature model with inflection (CTMI). As experienced by other authors, the RTK2, ZWT, and CTMI models provided the best statistical indices related to fitting the experimental data. Moreover, with the biological background, the following cardinal temperatures of L. rhamnosus GG resulted from the study by the model application: t min = 2.7°C, t opt = 44.4°C, t max = 52.0°C. The growth rate of the strain under study at optimal temperature was 0.88 log10(CFU mL−1 h−1).

Growth, development and allometry of Philophthalmus nocturnus in the eyes of domestic chicks

1992 ◽  
Vol 66 (2) ◽  
pp. 100-107 ◽  
Author(s):  
V. G. M. Swarnakumari ◽  
R. Madhavi
Keyword(s):  
Growth Rate ◽  
Developmental Stages ◽  
Adult Stage ◽  
The Body ◽  
Lag Phase ◽  
Allometric Growth ◽  
Body Width ◽  
Rapid Phase ◽  
Growth Development ◽  
Two Phases

ABSTRACTFifty day-old chicks were each infected with 10 excysted metaccreariae of Philophthalimus nocturnus Looss. 1907 around each orbit and growth, development and allometry were studied. The growth rate showed two phases over a period of 35 days, a limited lag phase lasting two days post-infection in which flukes did not exceed 440 μm in length, and a rapid phase during which growth was rapid and flukes reached a size of 3·008–3·504 mm on day 35. Five developmental stages were noticed during the course of development of the metacercaria to the egg-producing adult stage. Eggs appeared in the uterus on day 14 and oculate miracidia on day 25. The hindhody, testes and ovary showed positive allometric growth, the pharnyx less so, whereas negative allometric growth was shown by the forebody. Body width, oral sucker and ventral sucker were close to isometry, growing at the same rate as the body length.

Validation and Analysis of Modeled Predictions of Growth of Bacillus cereus Spores in Boiled Rice

2000 ◽  
Vol 63 (2) ◽  
pp. 268-272 ◽  
Author(s):  
DANA M. McELROY ◽  
LEE-ANN JAYKUS ◽  
PEGGY M. FOEGEDING
Keyword(s):  
Growth Rate ◽  
Bacillus Cereus ◽  
Exponential Growth ◽  
Generation Time ◽  
Time Lag ◽  
Lag Phase ◽  
Exponential Growth Rate ◽  
Phase Duration ◽  
Margin Of Safety ◽  
Fail Safe

The growth of psychrotrophic Bacillus cereus 404 from spores in boiled rice was examined experimentally at 15, 20, and 30°C. Using the Gompertz function, observed growth was modeled, and these kinetic values were compared with kinetic values for the growth of mesophilic vegetative cells as predicted by the U.S. Department of Agriculture's Pathogen Modeling Program, version 5.1. An analysis of variance indicated no statistically significant difference between observed and predicted values. A graphical comparison of kinetic values demonstrated that modeled predictions were “fail safe” for generation time and exponential growth rate at all temperatures. The model also was fail safe for lag-phase duration at 20 and 30°C but not at l5°C. Bias factors of 0.55, 0.82, and 1.82 for generation time, lag-phase duration, and exponential growth rate, respectively, indicated that the model generally was fail safe and hence provided a margin of safety in its growth predictions. Accuracy factors of 1.82, 1.60, and 1.82 for generation time, lag-phase duration, and exponential growth rate, respectively, quantitatively demonstrated the degree of difference between predicted and observed values. Although the Pathogen Modeling Program produced reasonably accurate predictions of the growth of psychrotrophic B. cereus from spores in boiled rice, the margin of safety provided by the model may be more conservative than desired for some applications. It is recommended that if microbial growth modeling is to be applied to any food safety or processing situation, it is best to validate the model before use. Once experimental data are gathered, graphical and quantitative methods of analysis can be useful tools for evaluating specific trends in model prediction and identifying important deviations between predicted and observed data.

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