Biological Reaction Engineering

Dunn, Irving J.; Heinzle, Elmar; Ingham, John; Prenosil, J. E.

doi:10.1002/3527603050

Cited by 74 publications

(41 citation statements)

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“…The best way to control the addition of the feed is monitoring the concentration of the nutrient itself in the fermenter or reactor vessel. However, accumulations of toxic products to the microorganism in the medium and downtime due to charging and discharging (which also occur in batch fermentations) are the main disadvantages of Fed batch fermentation [12].…”

Section: Fed Batch Fermentationmentioning

confidence: 99%

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Continuous Agave Juice Fermentation for Producing Bioethanol

Diaz-Montaño¹

2013

Biomass Now - Sustainable Growth and Use

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Section: Fed Batch Fermentationmentioning

confidence: 99%

“…The Biomass, nutrients and products concentrations change continuously in time [12]. Where x is the concentration of microbial biomass t is time, in hours and μ is the specific growth rate in hours -1 d. Negative acceleration phase -Period in which there is a slow rise in population as the environmental resistance increases.…”

Section: Batch Fermentationmentioning

confidence: 99%

Continuous Agave Juice Fermentation for Producing Bioethanol

Diaz-Montaño¹

2013

Biomass Now - Sustainable Growth and Use

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“…The non linearity was because of change in ethanol concentration which caused a change in the enzymatic reaction order from first to zero order. As approved, the order of reaction will be changed from first order reaction for low substrate concentration to zero order for high substrate concentration (Dunn et al 2003;Murry, 2003;Lee 2001). Such nonlinear plot can not be used as a calibration curve for ethanol determination.…”

Section: Resultsmentioning

confidence: 99%

Quantification of Full Range Ethanol Concentrations by using pH Sensor

Al-mhanna¹,

Huebner²

2011

IJC

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A differential pH measurement device was used to achieve operation conditions of alcohol dehydrogenase reaction. Optimum operating conditions were temperature of 30°C, 10 µl of alcohol dehydrogenase enzyme volume (with a final activity of 563.75 units ml-1) per 50 µl of sample, NAD + concentration of 0.05 mM and 20 mM glycine-pyrophosphate buffer solution of pH 9.1. In this method a range of ethanol concentrations from 0 -99,985 %, which means 0.000001714 -17.14 M, were used. The maximum obtained change in pH, delta pH, was (-33) mpH. A calibration curve of logarithmic values of ethanol concentrations against change in pH for standard ethanol samples was done. Since this calibration curve is a linear with a correlation coefficient (R) of 0.998, this calibration curve can be used in quantification of ethanol concentration. End point of equilibrium concentrations of reactants and products of ethanol oxidation reaction was measured within spectrophotometer. The results indicated 100 seconds of process time is required to reach the end point for all ethanol standard samples. This required time was satisfied with results of measuring change in pH within differential pH analyzer system.

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“…The model consists of six ordinary differential equations, three kinetic terms and respective kinetic parameters. Kinetics of the model are of the additive Monod type for growth with mixed substrates (see, e.g., Dunn et al, 2003). Characteristic growth parameters of R. rubrum were determined in a set of shake-flask experiments containing succinate and fructose at different concentrations as well as by single substrate experiments.…”

Section: Modeling and Simulationmentioning

confidence: 99%

Model‐based high cell density cultivation of Rhodospirillum rubrum under respiratory dark conditions

Zeiger

Grammel

2009

Biotech & Bioengineering

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The potential of facultative photosynthetic bacteria as producers of photosynthetic pigments, vitamins, coenzymes and other valuable products has been recognized for decades. However, mass cultivation under photosynthetic conditions is generally inefficient due to the inevitable limitation of light supply when cell densities become very high. The previous development of a new cultivation process for maximal expression of photosynthetic genes under semi-aerobic dark conditions in common bioreactors offers a new perspective for utilizing the facultative photosynthetic bacterium Rhodospirillum rubrum for large-scale applications. Based on this cultivation system, the present study aimed in determining the maximal achievable cell density of R. rubrum in a bioreactor, thereby providing a major milestone on the way to industrial bioprocesses. As a starting point, we focus on aerobic growth due to higher growth rates and more facile process control under this condition, with the option to extend the process by an anaerobic production phase. Process design and optimization were supported by an unstructured computational process model, based on mixed-substrate kinetics. Key parameters for growth and process control were determined in shake-flask experiments or estimated by simulation studies. For fed-batch cultivation, a computer-controlled exponential feed algorithm in combination with a pH-stat element was implemented. As a result, a maximal cell density of 59 g cell dry weight (CDW) L(-1) was obtained, representing so far not attainable cell densities for photosynthetic bacteria. The applied exponential fed-batch methodology therefore enters a range which is commonly employed for industrial applications with microbial cells. The biochemical analysis of high cell density cultures revealed metabolic imbalances, such as the accumulation and excretion of tetrapyrrole intermediates of the bacteriochlorophyll biosynthetic pathway.

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Biological Reaction Engineering

Cited by 74 publications

References 0 publications

Continuous Agave Juice Fermentation for Producing Bioethanol

Continuous Agave Juice Fermentation for Producing Bioethanol

Quantification of Full Range Ethanol Concentrations by using pH Sensor

Model‐based high cell density cultivation of Rhodospirillum rubrum under respiratory dark conditions

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