scholarly journals A possible predictive mathematical model for the growth of a periphytic alga

2022 ◽  
Vol 2159 (1) ◽  
pp. 012004
Author(s):  
J Agredo ◽  
J Cárdenas-Poblador ◽  
M L Ortiz-Moreno ◽  
A Vega-Moreno
Keyword(s):  
Mathematical Model ◽  
Industrial Development ◽  
Algal Growth ◽  
Exponential Phase ◽  
Discrete Equation ◽  
Lag Phase ◽  
Study Analysis ◽  
Kinetic Behavior ◽  
Photosynthetic Organisms ◽  
Periphytic Alga

Abstract Algae are photosynthetic organisms and have qualities that are very attractive for cultivation and industrial development for commercial purposes. When algal growth is analyzed for the production of biomass usually only the exponential phase of the growth curve is considered and the other phases are ignored. The objective of the work is to present a possible predictive mathematical model that allows a better understanding of the kinetic behavior of a periphytic microalgae by means of the use of the Smoluchowski discrete equation, with special emphasis on the lag phase. More specifically, unknown connection between the discrete Smoluchowski equation and the deterministic Baranyi model is shown in the present study. Analysis of this connection leads to a possible predictive mathematical model about of the kinetic behavior of a periphytic microalgae.

scholarly journals Numerical Simulation of a New Porous Medium Burner with Two Sections and Double Decks

Processes ◽  
2018 ◽  
Vol 6 (10) ◽  
pp. 185 ◽  
Author(s):  
Zhenzhen Jia ◽  
Qing Ye ◽  
Haizhen Wang ◽  
He Li ◽  
Shiliang Shi
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Porous Medium ◽  
Industrial Development ◽  
High Efficiency ◽  
Methane Combustion ◽  
Combustion Mechanism ◽  
Gas Mixture ◽  
Temperature And Pressure ◽  
Save Energy

Porous medium burners are characterized by high efficiency and good stability. In this study, a new burner was proposed based on the combustion mechanism of the methane-air mixture in the porous medium and the preheating effect. The new burner is a two-section and double-deck porous medium with gas inlets at both ends. A mathematical model for the gas mixture combustion in the porous medium was established. The combustion performance of the burner was simulated under different equivalence ratios and inlet velocities of premixed gas. The methane combustion degree, as well as the temperature and pressure distribution, was estimated. In addition, the concentrations of emissions of NOx for different equivalence ratios were investigated. The results show that the new burner can not only realize sufficient combustion but also save energy. Furthermore, the emission concentration of NOx is very low. This study provides new insights into the industrial development and application of porous medium combustion devices.

scholarly journals Induction of a Global Stress Response during the First Step of Escherichia coli Plate Growth

2006 ◽  
Vol 73 (3) ◽  
pp. 885-889 ◽  
Author(s):  
Caroline Cuny ◽  
Ma�al�ne Lesbats ◽  
Sam Dukan
Keyword(s):  
Solid Medium ◽  
Physiological State ◽  
Luria Bertani ◽  
Medium Composition ◽  
Exponential Phase ◽  
Lag Phase ◽  
Wild Type ◽  
Two Dimensional Electrophoresis ◽  
And Oxidative Stress ◽  
Dimensional Electrophoresis

ABSTRACT We have investigated the first events that occur when exponentially grown cells are transferred from a liquid medium (Luria-Bertani [LB]) to a solid medium (LB agar [LBA]). We observed an initial lag phase of 180 min for the wild type MG1655 without any apparent growth. This lack of growth was independent of the bacterial physiological state (either the stationary or the exponential phase), the solid medium composition, or the number of cells on the plate, but it was dependent on the bacterial genotype. Using lacZ-reporter fusions and two-dimensional electrophoresis analysis, we observed that when cells from exponential-phase cultures were plated on LBA, several global regulons, like heat shock regulons (RpoH, RpoE, CpxAR) and oxidative-stress regulons (SoxRS, OxyR, Fur), were immediately induced. Our results indicate that in order to grow on plates, bacteria must not only adapt to new conditions but also perceive a real stress.

scholarly journals NUTRIENT MEDIUM SELECTION AND OPTIMIZATION OF AVIBACTERIUM PARAGALLINARUM DEEP CULTURE METHOD

2019 ◽  
pp. 12-16
Author(s):  
M. S. Firsova ◽  
V. A. Yevgrafova ◽  
A. V. Potekhin
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Growth Phase ◽  
Nutrient Medium ◽  
Specific Growth ◽  
Exponential Phase ◽  
Exponential Growth Phase ◽  
Lag Phase ◽  
Optimal Method ◽  
Avibacterium Paragallinarum

Different liquid nutrient media supplemented with growth factors intended for Avibacterium paragallinarum strain No. 5111 cultivation were com­pared. The highest specific growth rate (μ = 0.787 ± 0.041 h-1) and the maximal accumulation of the agent’s biomass (Х = 9.52 ± 0.04 lg CFU/ cm3) were reported when cultured in casein soybean broth. Herewith, the mean time of the live microbial cell concentration doubling was minimal (td = 0.88 h), and the exponential growth phase lasted for 6 hours. The optimal method for Avibacterium paragallinarum cultivation in casein soy­bean broth in laboratory bioreactor Biotron LiFlus GX was determined through the measurements and adjustment of basic physical and chemical parameters. The time period until the culture reached the stationary growth phase was maximal with aeration at 1.0 l/min; herewith, the O2 partial pressure in the nutrient medium did not exceed 25%. The period of the intense decrease of medium’s pH was accompanied with the exponential phase of the bacterial growth. The nutrient medium’s pH ranging from 7.30 ± 0.02 to 7.90 ± 0.06 had no significant impact on the specific growth rate of the strain and the lag phase duration was minimal – 0.36–0.45 h. The strain cultivation in the nutrient medium with pH 7.90 ± 0.06 demonstrated maximal aggregation of the bacteria (9.76 ± 0.04 lg CFU/cm3). 40% glucose solution added at 0.6-0.8 g/l during cultivation facilitated the decrease of the suspension’s pH. Minimal redox value (–75 mV) was indicative of the completion of the exponential phase of the strain growth.  

scholarly journals The metabolic profile of lag and exponential phases of Saccharomyces cerevisiae growth changes continuously

2016 ◽  
Author(s):  
Rafael N. Bento ◽  
Miguel A. Aradhya ◽  
Valdir A. R. Semedo ◽  
Carlos E. S. Bernardes ◽  
Manuel E. M. Piedade ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Metabolic Profile ◽  
Environmental Changes ◽  
Exponential Phase ◽  
Cellular Growth ◽  
Lag Phase ◽  
Continuous Increase ◽  
Flow Microcalorimetry ◽  
Growth Changes ◽  
Two Phases

AbstractCellular growth is usually separated in well-defined phases. For microorganism like Saccharomyces cerevisiae, two phases usually defined are (1) a lag phase, in which no growth is observed and cells adapt to a new environment, followed by (2) an exponential phase, in which rapid proliferation occurs. Here we investigate whether these well-defined phases are uniform. By using flow-microcalorimetry, we found that the metabolic profile of the culture is continuously changing, both in the lag and exponential phases of growth. Along the lag phase there is a continuous increase in the energy that is dissipated irreversibly as heat, while in the exponential phase the opposite occurs. We also confirm recent observations that the oxidative component of metabolism decreases along the exponential phase. Interestingly, nutrient limitation further decreases the amount of energy that is dissipated irreversibly. Altogether, this points to a picture in which cells respond rapidly to minute environmental changes by adjusting their metabolic profile.

scholarly journals Autocrine interleukin-1 beta regulates both proliferation and apoptosis in EL4-6.1 thymoma cells

Blood ◽  
1995 ◽  
Vol 85 (12) ◽  
pp. 3532-3537 ◽  
Author(s):  
M Fratelli ◽  
V Gagliardini ◽  
G Galli ◽  
P Gnocchi ◽  
P Ghiara ◽  
...  
Keyword(s):  
Cell Growth ◽  
Interleukin 1 ◽  
Exponential Phase ◽  
Lag Phase ◽  
Interleukin 1 Beta ◽  
Plateau Phase ◽  
Cell Type ◽  
Regulatory Factor ◽  
Proliferation And Apoptosis ◽  
Single Cell Type

We demonstrate here that EL4–6.1 cells, a mouse thymoma that expresses high levels of membrane interleukin (IL)-1 receptors, produce IL-1 beta as an autocrine regulatory factor. Endogenous IL-1 beta sustains both proliferation and apoptosis: during the exponential phase, it mainly promotes proliferation, while during the plateau phase of cell growth, it induces death by apoptosis. Additionally, we show that exogenous IL-1 beta added to EL4–6.1 cells in lag phase induces apoptosis in a portion of the cells and proliferation in the remaining cells. Therefore, IL-1 beta can exert two completely opposite effects on a single cell type, depending on the state of the target cell.

Effects of mycotoxins, aflatoxin B1 and deoxynivalenol, on the bioluminescence of Vibrio fischeri

2008 ◽  
Vol 1 (2) ◽  
pp. 189-193 ◽  
Author(s):  
S. Sarter ◽  
I. Metayer ◽  
N. Zakhia
Keyword(s):  
Aflatoxin B1 ◽  
Light Emission ◽  
Vibrio Fischeri ◽  
Exponential Phase ◽  
Lag Phase ◽  
Bioluminescence Inhibition ◽  
Aflatoxin B

The effects of aflatoxin B1 and deoxynivalenol on the luminescence of Vibrio fischeri were investigated to determine the conditions of using the bioluminescence as an indirect means for mycotoxin detection. The culture of Vibrio fischeri showed that bioluminescence reached a peak after 12 hours of incubation at 25 °C and then decreased drastically. During the lag phase which lasted 6 hours, light emission decreased drastically for both the mycotoxin assays – aflatoxin B1 10 µg/ml and deoxynivalenol 20 µg/ml – and the corresponding controls. Distinct bioluminescence inhibition appeared after this period of minimal bioluminescence of the controls and started with the exponential phase of growth. The percentage of bioluminescence inhibition for both mycotoxins was determined after 3.5, 10, 15 and 25 hours of incubation. The bioluminescence of Vibrio fischeri was inhibited with aflatoxin B1 and enhanced with deoxynivalenol. Both effects were delayed and required a long-term incubation over 10 hours, which may help to investigate bioassays for mycotoxin detection.

Isolation of Bacillus cereus from Soft Soybean Curd, and Kinetic Behavior of the Isolates under Changing Temperature.

2021 ◽  
Author(s):  
Eunyoung Park ◽  
Hyemin Oh ◽  
Sejeong Kim ◽  
Jimyeong Ha ◽  
Yukyung Choi ◽  
...  
Keyword(s):  
Bacillus Cereus ◽  
Kinetic Parameters ◽  
Dynamic Model ◽  
Model Performance ◽  
Polynomial Equation ◽  
Lag Phase ◽  
Kinetic Behavior ◽  
Phase Duration ◽  
Cell Counts ◽  
Soybean Curd

This study isolated Bacillus cereus from soft soybean curds and developed a dynamic model to describe the kinetic behavior of B. cereus isolates during transfer and storage. B. cereus were first isolated from soft soybean curds. A mixture of B. cereus isolates was then inoculated in soft soybean curd and the bacterial cell counts were enumerated during storage at 10-30°C. The B. cereus cell counts were fitted to the Baranyi model to calculate growth rate ( µ max ; log CFU/g/h) and lag phase duration ( LPD ; h). These kinetic parameters were then analyzed with a polynomial equation to evaluate the effects of temperature on the kinetic parameters. The developed model was validated with observed values, and the differences between predicted and observed values were determined by calculating the root mean square error ( RMSE ). A dynamic model was then developed with a combination of primary and secondary models to describe B. cereus growth under changing temperature conditions B. cereus was detected in 2 soft soybean curd samples (5.1%) at 0.7 log CFU/g. The µ max ranged from -0.04 to 0.47 log CFU/g/h, and ln ( LPD ) ranged from 0.68 to 0.04 h, depending on storage temperatures. The model performance was appropriate with a 0.216 RMSE and accurately described the kinetic behavior of B. cereus in soft soybean curd samples. These results suggest that B. cereus can contaminate soft soybean curds and that the models developed with the B. cereus isolates are useful in describing the kinetic behavior of B. cereus in soft soybean curd.

Survival and Growth of Epidemically Successful and Nonsuccessful Salmonella enterica Clones after Freezing and Dehydration

2012 ◽  
Vol 75 (3) ◽  
pp. 456-464 ◽  
Author(s):  
KAROLINE MÜLLER ◽  
SØREN AABO ◽  
TINA BIRK ◽  
HANNE MORDHORST ◽  
BJÖRG BJARNADÓTTIR ◽  
...  
Keyword(s):  
Salmonella Typhimurium ◽  
Epidemiological Studies ◽  
Temperature Tolerance ◽  
Exponential Phase ◽  
Lag Phase ◽  
Industrialized Countries ◽  
High Temperature Tolerance ◽  
Low Humidity ◽  
Survival And Growth ◽  
Minced Meat

The spread of epidemically successful nontyphoidal Salmonella clones has been suggested as the most important cause of salmonellosis in industrialized countries. Factors leading to the emergence of success clones are largely unknown, but their ability to survive and grow after physical stress may contribute. During epidemiological studies, a mathematical model was developed that allowed estimation of a factor (q) accounting for the relative ability of Salmonella serovars with different antimicrobial resistances to survive in the food chain and cause human disease. Based on this q-factor, 26 Salmonella isolates were characterized as successful or nonsuccessful. We studied the survival and growth of stationary- and exponential-phase cells of these isolates after freezing for up to 336 days in minced meat. We also investigated survival and growth after dehydration at 10°C and 82% relative humidity (RH) and 25°C and 49% RH for 112 days. Stationary-phase cells were reduced by less than 1 log unit during 1 year of freezing, and growth was initiated with an average lag phase of 1.7 h. Survival was lower in exponential-phase cells, but lag phases tended to be shorter. High humidity and low temperature were less harmful to Salmonella than were low humidity and high temperature. Tolerance to adverse conditions was highest for Salmonella Infantis and one Salmonella Typhimurium U292 isolate and lowest for Salmonella Derby and one Salmonella Typhimurium DT170 isolate. Dehydration, in contrast to freezing, was differently tolerated by the Salmonella strains in this study, but tolerance to freezing and dehydration does not appear to contribute to the emergence of successful Salmonella clones.

Mathematical Models To Predict Kinetic Behavior and Growth Probabilities of Listeria monocytogenes on Pork Skin at Constant and Dynamic Temperatures

2013 ◽  
Vol 76 (11) ◽  
pp. 1868-1872 ◽  
Author(s):  
SOOMIN LEE ◽  
HEEYOUNG LEE ◽  
JOO-YEON LEE ◽  
PANAGIOTIS SKANDAMIS ◽  
BEOM-YOUNG PARK ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Root Mean Square Error ◽  
Mathematical Models ◽  
Mean Square Error ◽  
Root Mean Square ◽  
Storage Temperature ◽  
Lag Phase ◽  
Mean Square ◽  
Kinetic Behavior ◽  
A Value

In this study, mathematical models were developed to predict the growth probability and kinetic behavior of Listeria monocytogenes on fresh pork skin during storage at different temperatures. A 10-strain mixture of L. monocytogenes was inoculated on fresh pork skin (3 by 5 cm) at 4 log CFU/cm2. The inoculated samples were stored aerobically at 4, 7, and 10°C for 240 h, at 15 and 20°C for 96 h, and at 25 and 30°C for 12 h. The Baranyi model was fitted to L. monocytogenes growth data on PALCAM agar to calculate the maximum specific growth rate, lag-phase duration, the lower asymptote, and the upper asymptote. The kinetic parameters were then further analyzed as a function of storage temperature. The model simulated growth of L. monocytogenes under constant and changing temperatures, and the performances of the models were evaluated by the root mean square error and bias factor (Bf). Of the 49 combinations (temperature × sampling time), the combinations with significant growth (P < 0.05) of L. monocytogenes were assigned a value of 1, and the combinations with nonsignificant growth (P ≥ 0.05) were given a value of 0. These data were analyzed by logistic regression to develop a model predicting the probabilities of L. monocytogenes growth. At 4 to 10°C, obvious L. monocytogenes growth was observable after 24 h of storage; but, at other temperatures, the pathogen had obvious growth after 12 h of storage. Because the root mean square error value (0.184) and Bf (1.01) were close to 0 and 1, respectively, the performance of the developed model was acceptable, and the probabilistic model also showed good performance. These results indicate that the developed model should be useful in predicting kinetic behavior and calculating growth probabilities of L. monocytogenes as a function of temperature and time.

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