On-line carbon balance of yeast fermentations using miniaturized optical sensors

Beuermann, Thomas; Egly, Dominik; Geoerg, Daniel; Klug, Kerris Isolde; Storhas, Winfried; Methner, Frank‐Jürgen

doi:10.1016/j.jbiosc.2011.10.016

Cited by 22 publications

(18 citation statements)

References 27 publications

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“…We put special emphasis on the possibility to measure culture off‐gas in our bioreactor system since it is an important tool to determine crucial physiological respiration parameters like O 2 consumption and CPRs and to validate the accuracy of analytics and data consistency by carbon balancing. Various approaches for off‐gas analysis exist, either by mass spectrometry (Heinzle et al, 1990), photometrically (Beuermann et al, 2011), or by means of electrochemical sensors (van Leeuwen et al, 2010). Mass spectrometry however also permits the determination of isotopomers, which can be of advantage when isotopically labeled substrates are used.…”

Section: Discussionmentioning

confidence: 99%

A system of miniaturized stirred bioreactors for parallel continuous cultivation of yeast with online measurement of dissolved oxygen and off‐gas

Klein

Schneider

Heinzle

2012

Biotech & Bioengineering

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Chemostat cultivation is a powerful tool for physiological studies of microorganisms. We report the construction and application of a set of eight parallel small-scale bioreactors with a working volume of 10 mL for continuous cultivation. Hungate tubes were used as culture vessels connected to multichannel-peristaltic pumps for feeding fresh media and removal of culture broth and off-gas. Water saturated air is sucked into the bioreactors by applying negative pressure, and small stirrer bars inside the culture vessels allow sufficient mixing and oxygen transfer. Optical sensors are used for non-invasive online measurement of dissolved oxygen, which proved to be a powerful indicator of the physiological state of the cultures, particularly of steady-state conditions. Analysis of culture exhaust-gas by means of mass spectrometry enables balancing of carbon. The capacity of the developed small-scale bioreactor system was validated using the fission yeast Schizosaccharomyces pombe, focusing on the metabolic shift from respiratory to respiro-fermentative metabolism, as well as studies on consumption of different substrates such as glucose, fructose, and gluconate. In all cases, an almost completely closed carbon balance was obtained proving the reliability of the experimental setup.

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Section: Discussionmentioning

confidence: 99%

A system of miniaturized stirred bioreactors for parallel continuous cultivation of yeast with online measurement of dissolved oxygen and off‐gas

Klein

Schneider

Heinzle

2012

Biotech & Bioengineering

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“…The fermentations were carried out in a BIOSTAT ® E fermenter (Sartorius AG, Göttingen, Germany) consisting of a borosilicate glass vessel. Detailed information about the instrumentation of the bioreactor can be found in a previous publication [29].…”

Section: Cultivation Conditionsmentioning

confidence: 99%

“…During the first phase of the yeast fermentation, the carbon source glucose is mainly converted into ethanol and biomass. In the second phase, the product ethanol is consumed for biomass production [29,30]. Strong and characteristic MIR absorption bands for the detection of glucose and ethanol can be observed in a spectral range between approximately 800 cm −1 and 1400 cm −1 [20,21].…”

Section: Selection Of Spectral Ranges For Mlr and Pls Modelsmentioning

confidence: 99%

“…After the medium is depleted of glucose, an enzymatic adaption of the yeast cells with the aim to use the previously-formed ethanol as a new carbon substrate is observed [30]. In this phase of fermentation, the ethanol is converted into biomass and carbon dioxide [29,30]. Thereby the concentration of produced biomass increased to 10 g L −1 (biomass concentration including inoculum: 15 g L −1 ).…”

Section: Prediction Of Temporal Concentration Courses Using Mlr and Pmentioning

confidence: 99%

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Comparison of Raman and Mid-Infrared Spectroscopy for Real-Time Monitoring of Yeast Fermentations: A Proof-of-Concept for Multi-Channel Photometric Sensors

et al. 2019

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Raman and mid-infrared (MIR) spectroscopy are useful tools for the specific detection of molecules, since both methods are based on the excitation of fundamental vibration modes. In this study, Raman and MIR spectroscopy were applied simultaneously during aerobic yeast fermentations of Saccharomyces cerevisiae. Based on the recorded Raman intensities and MIR absorption spectra, respectively, temporal concentration courses of glucose, ethanol, and biomass were determined. The chemometric methods used to evaluate the analyte concentrations were partial least squares (PLS) regression and multiple linear regression (MLR). In view of potential photometric sensors, MLR models based on two (2D) and four (4D) analyte-specific optical channels were developed. All chemometric models were tested to predict glucose concentrations between 0 and 30 g L−1, ethanol concentrations between 0 and 10 g L−1, and biomass concentrations up to 15 g L−1 in real time during diauxic growth. Root-mean-squared errors of prediction (RMSEP) of 0.68 g L−1, 0.48 g L−1, and 0.37 g L−1 for glucose, ethanol, and biomass were achieved using the MIR setup combined with a PLS model. In the case of Raman spectroscopy, the corresponding RMSEP values were 0.92 g L−1, 0.39 g L−1, and 0.29 g L−1. Nevertheless, the simple 4D MLR models could reach the performance of the more complex PLS evaluation. Consequently, the replacement of spectrometer setups by four-channel sensors were discussed. Moreover, the advantages and disadvantages of Raman and MIR setups are demonstrated with regard to process implementation.

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“…In the scientific literature, much effort was put on the optimization of feeding control for sugar and other nutrients through mathematical models. Respiratory quotients were determined as part of various fed‐batch fermentation processes, including baker's yeast and antibiotics manufacturing (Johnson ; Reyman ; Beuermann and others ). In addition to the control of sugar, aeration was a very important limiting factor leading to reduced biomass yields through the production of excessive amounts of ethanol, which may have negative impact on the yeast resistance to stresses during bread manufacturing, including frozen dough (Gélinas and others ; Viera and others ).…”

Section: Sugar Concentration and Rate Of Additionmentioning

confidence: 99%

Fermentation Control in Baker's Yeast Production: Mapping Patents

Gélinas

2014

Comp Rev Food Sci Food Safe

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During baker's yeast manufacturing, the fermentation process must be thoroughly controlled. This review of the patent literature provides new information on the early development of industrial fermentation processes. As shown by a review of 199 patents filed between 1900 and 2009, inventors in this field were mainly interested to improve yeast yields through the control of infection and sugar concentration in the growth media. Contrary to common belief, much attention was also given to continuous culture processes, involving addition and withdrawal of growth media. These technologies were mainly developed in about 30 y, between 1910 and 1939. In the recent years, inventors gave sustained attention to the fine tuning of fermentation control, mainly the rapid determination of yeast fermentation by-products in the exhaust to get rapid feedback on the rate of sugar addition in the fermentation tank. Improved fermentation control benefited much the baking industry because baker's yeast had higher gassing power and was cheaper. However, some of these key patents on baker's yeast technology were later declared invalid in court because it had little intellectual property value. In the baker's yeast trade and other sectors, this situation might have encouraged trade secrets while reducing the credibility of innovative ideas disclosed in the patent literature.

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On-line carbon balance of yeast fermentations using miniaturized optical sensors

Cited by 22 publications

References 27 publications

A system of miniaturized stirred bioreactors for parallel continuous cultivation of yeast with online measurement of dissolved oxygen and off‐gas

A system of miniaturized stirred bioreactors for parallel continuous cultivation of yeast with online measurement of dissolved oxygen and off‐gas

Comparison of Raman and Mid-Infrared Spectroscopy for Real-Time Monitoring of Yeast Fermentations: A Proof-of-Concept for Multi-Channel Photometric Sensors

Fermentation Control in Baker's Yeast Production: Mapping Patents

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