Stirring characteristics in bioreactors

Vanags, Juris; Rikmanis, M.; Ushkans, E. J.; Viesturs, U.

doi:10.1002/aic.690360909

Cited by 13 publications

(7 citation statements)

References 13 publications

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“…In order to achieve a universality in readings of mixing intensity, we have developed a special instrument based on the piezoeffect, the Stirring Intensity Measuring Device (SIMD) [41], which was used for the comparison of results. SIMD measures the local kinetic energy (e) in bioreactors.…”

Section: Scale-up Of Bioreactors: Its Consequencesmentioning

confidence: 99%

“…A rarely used stirring system for growing of easily damaged microorganisms was described by Vanags et al [41]. The system consists of two conical discs with radial protrusions.…”

Section: Introductionmentioning

confidence: 99%

“…optical indication of insoluble or coloured tracer with the following calculation of the velocity and trajectory of the flow [31,32]. Several methods are employed to determine the local values of kinetic energy (e) of flow fluctuations by measuring the flow pressure on the submerged body [33][34][35][36][37][38][39][40][41][42][43][44]. This method is based on the turbulent multiphase flow interaction with the flow receiver head of the transducer.…”

Section: Introductionmentioning

confidence: 99%

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Excess turbulence as a cause of turbohypobiosis in cultivation of microorganisms

2007

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Abstract:The present review describes the influence of different types of mixing systems under excess turbulence conditions on microorganisms. Turbohypobiosis phenomena were described by applying a method for measurement of the kinetic energy of flow fluctuations based on the piezoeffect. It can be assumed that the shear stress effect (the state of turbohypobiosis) plays a role mainly when alternative mechanisms in cells cannot ensure a normal physiological state under stress conditions. Practically any system (inner construction of a bioreactor, culture and cultivation conditions, including mixing) requires its own optimisation to achieve the final goal, namely, the maximum product and/or biomass yields from substrate (Y P/S or/and Y X/S ), respectively. Data on the biotechnological performance of cultivation as well as power input, kinetic energy (e) of flow fluctuations, air consumption rate, rotational speed, tip speed, etc. do not correlate directly if the mixing systems (impellers-baffles) are dissimilar. Even the widely used specific power consumption cannot be relied upon for scaling up the cultivation performance using dissimilar mixing systems. A biochemical explanation for substrate and product transport via cell walls, carbon pathways, energy generation and utilisation, etc. furnishes insight into cellular interactions with turbulence of different origin for different types of microorganisms (single cells, mycelia forming cells, etc.

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Section: Scale-up Of Bioreactors: Its Consequencesmentioning

confidence: 99%

“…A rarely used stirring system for growing of easily damaged microorganisms was described by Vanags et al [41]. The system consists of two conical discs with radial protrusions.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Excess turbulence as a cause of turbohypobiosis in cultivation of microorganisms

2007

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“…) The least-squares regression sums up every observed error in (2) to yield an objective function. For parameter identification, we take the worst observed error of all experiments for an objective function.…”

Section: Evaluation Of the Model Parametersmentioning

confidence: 99%

“…They are mostly used in the production of enzymes, amino acids, antibiotics, etc. 1,2 However, for optimal cultivation performance, each specific system (culture + bioreactor) requires individual adjustment and optimisation of the cultivation conditions. 3 In our study 4 , an alternative concept of the global models, namely functional state modelling, has been used.…”

Section: Introductionmentioning

confidence: 99%

Modelling and Fuzzy-Decision-Making of Batch Cultivation of Saccharomyces cerevisiae using Different Mixing Systems

Petrov

Ilkova

2015

Chem.Biochem.Eng.Q.

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This study is focussed on the modelling and fuzzy-decision-making of impulse mixing and vibromixing for a Saccharomyces cerevisiae batch cultivation. Different substrate inhibition models (Monod, Aiba, Andrews, Haldane, Luong, Edward, and Han-Levenspiel) have been considered in order to explain the cell growth kinetics. The results obtained (correlation coefficient, Fisher coefficient, relative error and statistics l) show that all growth rate models are adequate and can be used for modelling. The investigations have shown that the most suitable for both mixing systems (according to the best statistical indicators) is the Luong growth rate model, which will be used for the process modelling. A fuzzy-decision-making procedure is developed with the initial conditions (maximal rotation speed for the impulse mixing and maximal amplitude for the vibromixing systems). The developed optimisation and results obtained have shown that the impulse mixing systems have better productiveness and better glucose assimilation. In addition, it is easier to realize this system.

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Studies of the mixing character and flow distribution in mycelial fermentation broths

Vanags

Viesturs

Priede³

1995

Acta Biotechnologica

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The influence of two mixing systems on the principal parameters of mycelial fermentations of Aspergillus niger, Fusicoccwn amygdali Del. and Fusarium moniliforme Sheld. as well as their metabolite citric acid, fusicoccin and gibberellic acid production was analyzed from the viewpoint of flow energy distribution in a bioreactor. The growth and metabolite synthesis during fermentation was compared' under different mixing conditions in the fermenter FU-8 with a turbine mixing system (TMS) and a counterflow mixing system (CMS). It was found that the growth, productivity and respiration characteristics as well as the morphology of these cultures varied dependent on the mixing system and agitation regime used. The counterflow mixing system was more favourable for large agglomerates (F. amygdali) or soft pellets (A. niger) forming fungi, while the turbine mixing system was more effective for F. moniliforme growing in the form of small clumps and f m l y dispersed hyphae. Flow characteristics under different mixing conditions were analyzed in a model fermenter. The kinetic energy of flow fluctuations was measured in gassed and ungassed water and different fermentation broth systems by using a Stimng Intensity Measuring Device (SIMD-Fl). The difference of the energy values at different points was better expressed in the fementer with a turbine mixing system in comparison with that having a counterflow mixing system. High viscous F. amygdali and A. niger broth provided higher energy values compared to water and low viscous F. moniliforme broth. It was observed that the intensity of growth and the intensity of the synthesis decreased at very high energy values, which was obviously connected to the influence of the irreversible shear stress on the mycelial morphology.

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Stirring characteristics in bioreactors

Cited by 13 publications

References 13 publications

Excess turbulence as a cause of turbohypobiosis in cultivation of microorganisms

Excess turbulence as a cause of turbohypobiosis in cultivation of microorganisms

Modelling and Fuzzy-Decision-Making of Batch Cultivation of Saccharomyces cerevisiae using Different Mixing Systems

Studies of the mixing character and flow distribution in mycelial fermentation broths

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