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On the influence of the experimental set-up on the heterogeneous heat response of E. coli K12

Procedia Food Science 2011年 1卷 1067-1072页

作者： Eva Van Derlinden Ivan Lule Kathleen Boons Jan Van Impe BioTeC - Chemical and Biochemical Process Technology and Control Department of Chemical Engineering Katholieke Universiteit Leuven Leuven Belgium

Preceding dynamic experiments with Escherichia coli K12 revealed disturbed growth curves when temperature surpasses the maximum growth temperature. In this work, heat stress dynamics are studied in relation with oxidative stress. Different experimental set-ups are selected that result in different oxygen concentrations. Experiments are performed in bioreactors with varying settings for aeration and stirring, and in test tubes. It is observed that there is a significant effect of the experimental set-up on the dynamics of E. coli K12: reducing the oxygen supplied improves survival. These findings emphasize on the importance of a well-considered selection of the experimental set-up.

关键词： heat stress oxidative stress E. coli subpopulations

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Developing next generation predictive models: a systems biology approach

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Procedia Food Science 2011年 1卷 965-971页

作者： Jan F. Van Impe Dominique Vercammen Eva Van Derlinden BioTeC – Chemical and Biochemical Process Technology and Control Department of Chemical Engineering Katholieke Universiteit Leuven Leuven Belgium

The applicability and reliability of existing predictive models can definitely be improved by unraveling the underlying mechanisms and incorporating intracellular (microscopic) information. Following a systems biology approach, the link between the intracellular fluxes and the extracellular measurements is established by techniques of metabolic flux analysis. Flux balance analysis (FBA) uses an objective function to derive, through optimization over the solution space of this underdetermined linear system, an intracellular flux distribution. This paper discusses the background of the FBA approach and focuses on important issues with respect to the implementation of FBA analysis when modeling dynamic systems.

关键词： metabolic network flux balance analysis predictive microbiology

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The heterogeneous heat stress response of Escherichia coli K12

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Procedia Food Science 2011年 1卷 1060-1066页

作者： Iris Cornet Eva Van Derlinden Astrid M. Cappuyns Wim Bruyninckx Agnes Kovacs Jan F. Van Impe BioTeC - Chemical and Biochemical Process Technology and Control Department of Chemical Engineering KULeuven Belgium Artesis University College AUHA Antwerp Belgium

When subjected to a temperature increase surpassing the maximum growth temperature (T max ) Escherichia coli K12 MG1655 populations react heterogeneously, i.e. a sensitive and a resistant population seem to exist. The influence of heat stress adaptation on the model parameters of a heterogeneous model is quantified. In the conditions under study, the growth rate of the resistant population was affected only at the higher temperatures. For the sensitive subpopulation, T max,S , as described by the CTMI model, seemed to be influenced, with an increasing maximum growth temperature at a higher heating rate.

关键词： Escherichia coli heat resistant heterogeneity modeling temperature increase

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Anaerobic digestion of biomass and waste: Current trends in mathematical modeling

Anaerobic digestion of biomass and waste: Current trends in ...

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作者： Dewil, Raf Lauwers, Joost Appels, Lise Gins, Geert Degrève, Jan Van Impe, Jan Chemical and Biochemical Process Technology and Control Section Department of Chemical Engineering Katholieke Universiteit Leuven W. De Croylaan 46 B-3001 Heverlee Belgium

ISBN: (纸本)9783902661937

Although anaerobic digestion is a widely applied technology, the process is not yet fully understood because of its high complexity, and an optimization of the current technology is still needed. The design and control of digester systems is still generally performed by rule-of-thumb since no tools are currently available for an accurate evaluation of performance. The application of mathematical models is a prerequisite to improve digester performance and hence much attention is focused on the development of accurate models. This paper critically reviews the current state of the art about mathematical modeling of anaerobic digestion models. Moreover, the main trends in optimization of the existing models and the development of new models are discussed. © 2011 IFAC.

关键词： Anaerobic digestion

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Quantifying the combined effect of salt and temperature on the growth of Listeria strains isolated from salmon and salmon processing environments

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Procedia Food Science 2011年 1卷 1001-1006页

作者： Torstein Skåra Astrid M Cappuyns Eva Van Derlinden Jan Thomas Rosnes Vasilis P Valdramidis Jan FM Van Impe Nofima Stavanger Norway Katholieke Universiteit Leuven Department of Chemical Engineering BioTeC - Chemical and Biochemical Process Technology and Control Leuven Belgium Biosystems Engineering UCD School of Agriculture Food Science and Veterinary Medicine University College Dublin Ireland

The effects of temperature and salt concentration on the growth of relevant strains of L. monocytogenes and Listeria innocua , were quantified based on growth in a liquid broth medium, monitored by measuring turbidity. Absorbance curves were used to estimate maximum growth rate and lag time. The growth rates increase with increasing temperatures. The levels were quite similar for both species, although L. monocytogenes showed higher growth rate than L . innocua at 4 °C. Lag time was more affected both by temperature and salt concentration, and these effects were most prominent for L. innocua .

关键词： Listeria turbidity modelling salt temperature

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A thermodynamic approach to assess a cellular mechanism of inactivation and the thermal resistance of Listeria innocua

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Procedia Food Science 2011年 1卷 972-978页

作者： Torstein Skåra Astrid M Cappuyns Sissel O Johnsen Eva Van Derlinden Jan Thomas Rosnes Øystein Olsen Jan FM Van Impe Vasilis P Valdramidis Nofima PO Box 8034 N-4068 Stavanger Norway Katholieke Universiteit Leuven Department of Chemical Engineering BioTeC - Chemical and Biochemical Process Technology and Control Leuven Belgium Biosystems Engineering UCD School of Agriculture Food Science and Veterinary Medicine University College Dublin Dublin Ireland

In order to link kinetic data of isothermally inactivated planktonic cells to the enthalpy changes observed in pellet analysed in the DSC, two strains of Listeria innocua were investigated. Isothermal inactivation of planktonic cells showed z -values of 4.71 o C for L. innocua ATCC 33090 and 5.15 o C for CCUG 35613(= ATCC 51742). The results of the DSC analyses showed a linearly decreasing remaining enthalpy with increasing dynamic preheating temperature (from 20 to 66-80 o C). Deriving equivalent isothermal temperatures, the temperature profiles could be directly correlated with the microbial enthalpy changes, indicating that ribosome denaturation is not the inactivation mechanism for the low thermal treatments studied.

关键词： Listeria inactivation Differential Scanning Calorimetry ribosome denaturation

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Anaerobic digestion of biomass and waste: current trends in mathematical modeling

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IFAC Proceedings Volumes 2011年第1期44卷 5024-5033页

作者： Raf Dewil Joost Lauwers Lise Appels Geert Gins Jan Degrève Jan Van Impe Chemical and Biochemical Process Technology and Control Section Department of Chemical Engineering Katholieke Universiteit Leuven W. De Croylaan 46 B-3001 Heverlee Belgium (Tel: +32-16-322675)

Abstract Although anaerobic digestion is a widely applied technology, the process is not yet fully understood because of its high complexity, and an optimization of the current technology is still needed. The design and control of digester systems is still generally performed by rule-of-thumb since no tools are currently available for an accurate evaluation of performance. The application of mathematical models is a prerequisite to improve digester performance and hence much attention is focused on the development of accurate models. This paper critically reviews the current state of the art about mathematical modeling of anaerobic digestion models. Moreover, the main trends in optimization of the existing models and the development of new models are discussed.

关键词： anaerobic digestion ADM1 modeling

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Heat adaptation of Escherichia coli K12: Effect of acid and glucose

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Procedia Food Science 2011年 1卷 987-993页

作者： Eirini G. Velliou Eva Van Derlinden Astrid M. Cappuyns Jef Goossens Annemie H. Geeraerd Frank Devlieghere Jan F. Van Impe BioTeC-Chemical and Biochemical Process Technology and Control Department of Chemical Engineering Katholieke Universiteit Leuven W. de Croylaan 46 B-3001 Leuven Belgium MeBioS-Division of Mechatronics Biostatistics and Sensors Department of Biosystems Katholieke Universiteit Leuven W. de Croylaan 42 B-3001 Leuven Belgium Laboratory of Food Microbiology and Food Preservation Department of Food Technology and Nutrition Ghent University Coupure Links 653 B-9000 Ghent Belgium

The objective of this work is to investigate the effect of the (possible) acid adaptation during growth in a glucose rich environment on the heat resistance of Escherichia coli K12 MG1655. E. coli cells were grown in TSB and/or TSB dextrose free broth until they reached the stationary phase. Afterwards, the stationary phase cells were added in TSB and/or TSB dextrose free broth and inactivation took place at 54 o C and 58 o C. It was observed that growth in a glucose rich environment leads to an increased heat resistance, most likely due to a certain level of acid and further heat adaptation via cross protection.

关键词： E. coli acid adaptation heat resistance cross protection glucose

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Modeling microbial kinetics as a function of temperature: Identification of the growth/inactivation interface

Modeling microbial kinetics as a function of temperature: Id...

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作者： Van Derlinden, E. Van Impe, J.F. Department of Chemical Engineering BioTeC - Chemical and Biochemical Process Technology and Control Katholieke Universiteit Leuven W. de Croylaan 46 B-3001 Leuven Belgium

ISBN: (纸本)9783902661708

A previous implementation of dynamic experiments for the estimation of the parameters of the Cardinal Temperature Model with Inflection (CTMI), which describes the temperature effect on the microbial growth rate, revealed that the maximum growth temperature (Tmax) can only be estimated accurately when temperatures close to the true Tmax are included. As such, a reliable Tmax estimate is required at the beginning of the OED/PE implementation. Here, alternative experiments in which the temperature exceeds the growth/inactivation interface are evaluated. Results from the simulation study show that the accuracy and reliability of the Tmax estimate depends on the selected temperature profile. A very accurate and realistic Tmax value is obtained from experiments with an initial temperature slightly lower than the true Tmax. When the dynamic temperature starts at temperatures above Tmax, a larger uncertainty and variability is observed. From this, it can be concluded that information with respect to growth at temperatures close to Tmax is required for an accurate and reliable Tmax estimate. In a second step, two dynamic temperature profiles are implemented in a computer controlled bioreactor. The experimental data do not result in an accurate and reliable estimation of T max. Additional dynamic experiments are required to evaluate the proposed experimental set-up. © 2010 IFAC.

关键词： Parameter estimation

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Quantification of MTBE and TBA biodegradation

Quantification of MTBE and TBA biodegradation

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作者： Cappuyns, Astrid M. Debor, Linde J. Smets, Ilse Y. Springael, Dirk Bastiaens, Leen Van Impe, Jan F. BioTeC - Chemical and Biochemical Process Technology and Control Katholieke Universiteit Leuven W. de Croylaan 46 B-3001 Leuven Belgium Boeretang 200 B-2400 Mol Belgium Division Soil and Water Management Katholieke Universiteit Leuven Kasteelpark Arenberg 20 B-3001 Leuven Belgium

ISBN: (纸本)9783902661708

Methyl tertiary butyl ether or MTBE is often used as an additive in gasoline to boost the octane rating and to promote more efficient combustion of the gasoline. This widespread use of MTBE has resulted in serious soil and groundwater pollution. To tackle MTBE contamination in groundwater, bioremediation is considered a cost-effective and energy-efficient option. The design of an efficient, reliable and reproducible bioremediation strategy requires a thorough understanding of the (microbial) degradation kinetics of both MTBE and TBA (tertiary butyl alcohol), i.e., the main intermediate during bioremediation of MTBE. To assist the design procedure, this research focuses on building a low complexity, yet accurate mathematical model to describe MTBE/TBA degradation kinetics by a bacterial consortium, i.e., the VITO Mconsortium. The resulting model provides an accurate description of MTBE/TBA degradation and has successfully been validated on independent experimental data. Since the model is of the mass balance type, it can easily be extended to other types of operation by defining the transport terms of the new system. This makes the model a very useful tool in the design procedure for large scale bioremediation strategies. Furthermore, the model provides insight in the MTBE/TBA degradation kinetics and biodegradation mechanisms by hypothesis testing. © 2010 IFAC.

关键词： Bioremediation

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