The Experts below are selected from a list of 441990 Experts worldwide ranked by ideXlab platform
Jochen Buchs - One of the best experts on this subject based on the ideXlab platform.
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easy to use and reliable technique for online dissolved oxygen tension measurement in shake flasks using infrared fluorescent oxygen sensitive nanoparticles
Microbial Cell Factories, 2016Co-Authors: David Flitsch, Tobias Ladner, Mihaly Lukacs, Jochen BuchsAbstract:Despite the progressive miniaturization of bioreactors for screening purposes, shake flasks are still widespread in biotechnological laboratories and industry as Cultivation vessels. Shake flasks are often applied as the first or second step in applications such as strain screening or media optimization. Thus, there are ongoing efforts to develop online measurement techniques for shake flasks, to gain as much information as possible about the cultured microbial system. Since dissolved oxygen tension (DOT) is a key experimental parameter, its accurate determination during the course of experiment is critical. Some of the available DOT measurement techniques can lead to erroneous measurements or are very difficult to handle. A reliable and easy to use DOT measurement system, based on suspended oxygen-sensitive nanoparticles, is presented in this work. In a Cultivation of Kluyveromyces lactis, a new DOT measurement technique via suspended oxygen-sensitive nanoparticles was compared with the conventional DOT measurement via fixed sensor spots. These experiments revealed the main disadvantage of applying sensor spots. With further Cultivations of Escherichia coli and Hansenula polymorpha, the new measurement technique was successfully validated. In combination with a RAMOS device, kLa values were determined during the presented Cultivations. The determined kLa values are in good agreement with a correlation recently found in the literature. The presented DOT measurement technique via suspended oxygen-sensitive nanoparticles in shake flasks turned out to be easy to use, robust and reliable under all applied combinations of shaking frequencies and filling volumes. Its applicability as an online monitoring system for Cultivations was shown by means of four examples. Additionally, in combination with a RAMOS device, the possibility of experimental kLa determination was successfully demonstrated.
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Additional file 1: of Oxygen transfer rate identifies priming compounds in parsley cells
2015Co-Authors: Jana Schilling, Britta Schillheim, Stefan Mahr, Yannik Reufer, Sandi Sanjoyo, Uwe Conrath, Jochen BuchsAbstract:Reference Cultivations for the SA-dose dependent responses of parsley cell suspension cultures. A-C: Oxygen transfer rate (OTR) as a function of time for three salicylic acid (SA) concentrations: (A) addition of 10 μM SA, (B) addition of 50 μM SA, (C) addition of 100 μM SA. Cultivations: w/o additives (black squares), with the addition of exclusively SA after 72 h (blue diamonds), with the addition of exclusively 50 pM Pep13 after 96 h (gray up triangles), and with the addition of SA and 50 pM Pep13 (blue circles). Dotted lines indicate the addition of (1) SA, (2) Pep13, and (3) sampling for the furanocoumarin fluorescence measurements. D-E: The experiments are compared at an excitation wavelength of 335 nm and an emission wavelength of 400 nm. Cultivations: w/o additives (black columns), with the addition of exclusively salicylic acid (SA) (blue columns), with the addition of exclusively 50 pM Pep13 (gray columns), and with the addition of SA and 50 pM Pep13 (green, light blue and dark blue columns). Cultivation conditions: 250 mL flask volume, 50 mL filling volume, 180 rpm shaking frequency, 5 cm shaking diameter, and 25 °C. (TIF 16034 kb
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Additional file 3: of Oxygen transfer rate identifies priming compounds in parsley cells
2015Co-Authors: Jana Schilling, Britta Schillheim, Stefan Mahr, Yannik Reufer, Sandi Sanjoyo, Uwe Conrath, Jochen BuchsAbstract:Reference Cultivations for the Pep13-dose dependent responses of parsley cell suspension cultures. Oxygen transfer rate (OTR) as a function of time for three Pep13 concentrations: (A) addition of 100 pM Pep13, (B) addition of 50 pM Pep13, (C) addition of 1 pM Pep13. Cultivations: w/o additives (black squares), with the addition of exclusively 100 μM SA after 72 h (blue diamonds), with the addition of exclusively Pep13 after 96 h (gray up triangles), and with the addition of 100 μM SA and Pep13 (green circles). Dotted lines indicate the addition of (1) SA, (2) Pep13, and (3) sampling for the furanocoumarin fluorescence measurements. D-E: The experiments are compared at an excitation wavelength of 335 nm and an emission wavelength of 400 nm. Cultivations: w/o additives (black columns), with the addition of exclusively salicylic acid (SA) (blue columns), with the addition of exclusively 50 pM Pep13 (gray columns), and with the addition of 100 μM SA and 50 pM Pep13 (green columns). Cultivation conditions: 250 mL flask volume, 50 mL filling volume, 180 rpm shaking frequency, 5 cm shaking diameter, and 25 °C. (TIF 4013 kb
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Additional file 2: of Oxygen transfer rate identifies priming compounds in parsley cells
2015Co-Authors: Jana Schilling, Britta Schillheim, Stefan Mahr, Yannik Reufer, Sandi Sanjoyo, Uwe Conrath, Jochen BuchsAbstract:Additional Cultivations for the SA-dose dependent responses of parsley cell suspension cultures. A-C: Oxygen transfer rate (OTR) as a function of time for three salicylic acid (SA) concentrations: (A) addition of 1 μM SA, (B) addition of 100 μM SA, (C) addition of 200 μM SA. Cultivations: w/o additives (black squares), with the addition of exclusively SA after 72 h (blue diamonds), with the addition of exclusively 50 pM Pep13 after 96 h (gray up triangles), and with the addition of SA and 50 pM Pep13 (purple circles). Dotted lines indicate the addition of (1) SA, (2) Pep13, and (3) sampling for the furanocoumarin fluorescence measurements. D-E: The experiments are compared at an excitation wavelength of 335 nm and an emission wavelength of 400 nm. Cultivations: w/o additives (black columns), with the addition of exclusively salicylic acid (SA) (blue columns), with the addition of exclusively 50 pM Pep13 (gray columns), and with the addition of SA and 50 pM Pep13 (purple columns). Cultivation conditions: 250 mL flask volume, 50 mL filling olume, 180 rpm shaking frequency, 5 cm shaking diameter, and 25 °C. (TIF 16270 kb
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phenotyping the quality of complex medium components by simple online monitored shake flask experiments
Microbial Cell Factories, 2014Co-Authors: Sylvia Diederichs, Anna Korona, Antje Staaden, Wolfgang Kroutil, Kohsuke Honda, Hisao Ohtake, Jochen BuchsAbstract:Media containing yeast extracts and other complex raw materials are widely used for the Cultivation of microorganisms. However, variations in the specific nutrient composition can occur, due to differences in the complex raw material ingredients and in the production of these components. These lot-to-lot variations can affect growth rate, product yield and product quality in laboratory investigations and biopharmaceutical production processes. In the FDA's Process Analytical Technology (PAT) initiative, the control and assessment of the quality of critical raw materials is one key aspect to maintain product quality and consistency. In this study, the Respiration Activity Monitoring System (RAMOS) was used to evaluate the impact of different yeast extracts and commercial complex auto-induction medium lots on metabolic activity and product yield of four recombinant Escherichia coli variants encoding different enzymes. Under non-induced conditions, the oxygen transfer rate (OTR) of E. coli was not affected by a variation of the supplemented yeast extract lot. The comparison of E. coli Cultivations under induced conditions exhibited tremendous differences in OTR profiles and volumetric activity for all investigated yeast extract lots of different suppliers as well as lots of the same supplier independent of the E. coli variant. Cultivation in the commercial auto-induction medium lots revealed the same reproducible variations. In Cultivations with parallel offline analysis, the highest volumetric activity was found at different Cultivation times. Only by online monitoring of the cultures, a distinct Cultivation phase (e.g. glycerol depletion) could be detected and chosen for comparable and reproducible offline analysis of the yield of functional product. This work proves that Cultivations conducted in complex media may be prone to significant variation in final product quality and quantity if the quality of the raw material for medium preparation is not thoroughly checked. In this study, the RAMOS technique enabled a reliable and reproducible screening and phenotyping of complex raw material lots by online measurement of the respiration activity. Consequently, complex raw material lots can efficiently be assessed if the distinct effects on culture behavior and final product quality and quantity are visualized.
Yahong Geng - One of the best experts on this subject based on the ideXlab platform.
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sequential phototrophic mixotrophic Cultivation of oleaginous microalga graesiella sp wbg 1 in a 1000 m 2 open raceway pond
Biotechnology for Biofuels, 2019Co-Authors: Xiaobin Wen, Huanping Tao, Xinan Peng, Zhongjie Wang, Yi Ding, Lin Liang, Aoqi Zhang, Caixia Liu, Yahong GengAbstract:Microalgae are an important feedstock in industries. Currently, efforts are being made in the non-phototrophic Cultivation of microalgae for biomass production. Studies have shown that mixotrophy is a more efficient process for producing algal biomass in comparison to phototrophic and heterotrophic cultures. However, Cultivation of microalgae in pilot-scale open ponds in the presence of organic carbon substrates has not yet been developed. The problems are heterotrophic bacterial contamination and inefficient conversion of organic carbon. Laboratory investigation was combined with outdoor Cultivation to find a culture condition that favors the growth of alga, but inhibits bacteria. A window period for mixotrophic Cultivation of the alga Graesiella sp. WBG-1 was identified. Using this period, a new sequential phototrophic–mixotrophic Cultivation (SPMC) method that enhances algal biomass productivity and limits bacteria contamination at the same time was established for microalgae Cultivation in open raceway ponds. Graesiella sp. WBG-1 maximally produced 12.5 g biomass and 4.1 g lipids m−2 day−1 in SPMC in a 1000 m2 raceway pond, which was an over 50% increase compared to phototrophic Cultivation. The bacterial number in SPMC (2.97 × 105 CFU ml−1) is comparable to that of the phototrophic Cultivations. SPMC is an effective and feasible method to cultivate lipid-rich microalgae in open raceway ponds. Successful scale-up of SPMC in a commercial raceway pond (1000 m2 culture area) was demonstrated for the first time. This method is attractive for global producers of not only lipid-rich microalgae biomass, but also astaxanthin and β-carotene.
Xiaobin Wen - One of the best experts on this subject based on the ideXlab platform.
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Sequential phototrophic–mixotrophic Cultivation of oleaginous microalga Graesiella sp. WBG-1 in a 1000 m2 open raceway pond
BMC, 2019Co-Authors: Xiaobin Wen, Huanping Tao, Xinan Peng, Zhongjie Wang, Yi Ding, Lin Liang, Aoqi Zhang, Caixia LiuAbstract:Abstract Background Microalgae are an important feedstock in industries. Currently, efforts are being made in the non-phototrophic Cultivation of microalgae for biomass production. Studies have shown that mixotrophy is a more efficient process for producing algal biomass in comparison to phototrophic and heterotrophic cultures. However, Cultivation of microalgae in pilot-scale open ponds in the presence of organic carbon substrates has not yet been developed. The problems are heterotrophic bacterial contamination and inefficient conversion of organic carbon. Results Laboratory investigation was combined with outdoor Cultivation to find a culture condition that favors the growth of alga, but inhibits bacteria. A window period for mixotrophic Cultivation of the alga Graesiella sp. WBG-1 was identified. Using this period, a new sequential phototrophic–mixotrophic Cultivation (SPMC) method that enhances algal biomass productivity and limits bacteria contamination at the same time was established for microalgae Cultivation in open raceway ponds. Graesiella sp. WBG-1 maximally produced 12.5 g biomass and 4.1 g lipids m−2 day−1 in SPMC in a 1000 m2 raceway pond, which was an over 50% increase compared to phototrophic Cultivation. The bacterial number in SPMC (2.97 × 105 CFU ml−1) is comparable to that of the phototrophic Cultivations. Conclusions SPMC is an effective and feasible method to cultivate lipid-rich microalgae in open raceway ponds. Successful scale-up of SPMC in a commercial raceway pond (1000 m2 culture area) was demonstrated for the first time. This method is attractive for global producers of not only lipid-rich microalgae biomass, but also astaxanthin and β-carotene
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sequential phototrophic mixotrophic Cultivation of oleaginous microalga graesiella sp wbg 1 in a 1000 m 2 open raceway pond
Biotechnology for Biofuels, 2019Co-Authors: Xiaobin Wen, Huanping Tao, Xinan Peng, Zhongjie Wang, Yi Ding, Lin Liang, Aoqi Zhang, Caixia Liu, Yahong GengAbstract:Microalgae are an important feedstock in industries. Currently, efforts are being made in the non-phototrophic Cultivation of microalgae for biomass production. Studies have shown that mixotrophy is a more efficient process for producing algal biomass in comparison to phototrophic and heterotrophic cultures. However, Cultivation of microalgae in pilot-scale open ponds in the presence of organic carbon substrates has not yet been developed. The problems are heterotrophic bacterial contamination and inefficient conversion of organic carbon. Laboratory investigation was combined with outdoor Cultivation to find a culture condition that favors the growth of alga, but inhibits bacteria. A window period for mixotrophic Cultivation of the alga Graesiella sp. WBG-1 was identified. Using this period, a new sequential phototrophic–mixotrophic Cultivation (SPMC) method that enhances algal biomass productivity and limits bacteria contamination at the same time was established for microalgae Cultivation in open raceway ponds. Graesiella sp. WBG-1 maximally produced 12.5 g biomass and 4.1 g lipids m−2 day−1 in SPMC in a 1000 m2 raceway pond, which was an over 50% increase compared to phototrophic Cultivation. The bacterial number in SPMC (2.97 × 105 CFU ml−1) is comparable to that of the phototrophic Cultivations. SPMC is an effective and feasible method to cultivate lipid-rich microalgae in open raceway ponds. Successful scale-up of SPMC in a commercial raceway pond (1000 m2 culture area) was demonstrated for the first time. This method is attractive for global producers of not only lipid-rich microalgae biomass, but also astaxanthin and β-carotene.
Waldir Desiderio Estela Escalante - One of the best experts on this subject based on the ideXlab platform.
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influencia de la aireacion en la actividad fermentativa de kloeckera apiculata durante la fermentacion de jugo de manzana
Acta Biológica Colombiana, 2012Co-Authors: Waldir Desiderio Estela EscalanteAbstract:The influence of aireation on the fermentative activity of Kloeckera apiculata RIVE 9-2-1 was studied in order to evaluate the production of metabolites of the fermentation. To achieve this, the strain was cultured in Erlenmeyer flasks containing sterilized and aroma removed apple juice, and the chemical compounds produced during fermentation in shaken (200 min-1) and static (without agitation) Cultivation were determined. The results showed that the agitation of the culture medium increases production of higher alcohols (till 591.0 mg/L) compared to static Cultivation, whereas on the contrary, the production of acetic acid, ethyl acetate and glycerol (260.0 ± 11.0 mg/L, 196.0 ± 10.0 mg/L y 2.6±0.2 g/L) were higher compared to shaken Cultivation (222.0 ± 8.0 mg/L, 96.0 ± 4.5 mg/L and 1.8 ± 0.2 g/L) respectively. Batch Cultivations carried out in bioreactor with air flux of 25 l/h reported a growth rate (µ) of 0.17 h-1, production of ethanol (12.5 ± 2.0 g/L) and other compounds typically produced during alcoholic fermentation. The concentration of dissolved oxygen in the fermentation medium affects its metabolism thus; insufficient amounts of oxygen would provoke a respirofermentative metabolism. The best results in terms of organoleptic quality of the fermented beverage regarding to aroma, taste and flavour was obtained when fermented in static Cultivation. The control of aeration during fermentation can be used to control the synthesis of chemical compounds of sensory impact in the production of fermented beverages.
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influencia de la aireacion en la actividad fermentativa de kloeckera apiculata durante la fermentacion de jugo de manzana
Acta Biológica Colombiana, 2012Co-Authors: Waldir Desiderio Estela EscalanteAbstract:The influence of aireation on the fermentative activity of Kloeckera apiculata RIVE 9-2-1 was studied in order to evaluate the production of metabolites of the fermentation. To achieve this, the strain was cultured in Erlenmeyer flasks containing sterilized and aroma removed apple juice, and the chemical compounds produced during fermentation in shaken (200 min-1) and static (without agitation) Cultivation were determined. The results showed that the agitation of the culture medium increases production of higher alcohols (till 591.0 mg/L) compared to static Cultivation, whereas on the contrary, the production of acetic acid, ethyl acetate and glycerol (260.0 ± 11.0 mg/L, 196.0 ± 10.0 mg/L y 2.6±0.2 g/L) were higher compared to shaken Cultivation (222.0 ± 8.0 mg/L, 96.0 ± 4.5 mg/L and 1.8 ± 0.2 g/L) respectively. Batch Cultivations carried out in bioreactor with air flux of 25 l/h reported a growth rate (µ) of 0.17 h-1, production of ethanol (12.5 ± 2.0 g/L) and other compounds typically produced during alcoholic fermentation. The concentration of dissolved oxygen in the fermentation medium affects its metabolism thus; insufficient amounts of oxygen would provoke a respirofermentative metabolism. The best results in terms of organoleptic quality of the fermented beverage regarding to aroma, taste and flavour was obtained when fermented in static Cultivation. The control of aeration during fermentation can be used to control the synthesis of chemical compounds of sensory impact in the production of fermented beverages.
Tobias Klein - One of the best experts on this subject based on the ideXlab platform.
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exploring small scale chemostats to scale up microbial processes 3 hydroxypropionic acid production in s cerevisiae
Microbial Cell Factories, 2019Co-Authors: Alicia V. Lis, Konstantin Schneider, Jost Weber, Jay D. Keasling, Michael Krogh Jensen, Tobias KleinAbstract:The physiological characterization of microorganisms provides valuable information for bioprocess development. Chemostat Cultivations are a powerful tool for this purpose, as they allow defined changes to one single parameter at a time, which is most commonly the growth rate. The subsequent establishment of a steady state then permits constant variables enabling the acquisition of reproducible data sets for comparing microbial performance under different conditions. We performed physiological characterizations of a 3-hydroxypropionic acid (3-HP) producing Saccharomyces cerevisiae strain in a miniaturized and parallelized chemostat Cultivation system. The physiological conditions under investigation were various growth rates controlled by different nutrient limitations (C, N, P). Based on the Cultivation parameters obtained subsequent fed-batch Cultivations were designed. We report technical advancements of a small-scale chemostat Cultivation system and its applicability for reliable strain screening under different physiological conditions, i.e. varying dilution rates and different substrate limitations (C, N, P). Exploring the performance of an engineered 3-HP producing S. cerevisiae strain under carbon-limiting conditions revealed the highest 3-HP yields per substrate and biomass of 16.6 %C-mol and 0.43 g gCDW−1, respectively, at the lowest set dilution rate of 0.04 h−1. 3-HP production was further optimized by applying N- and P-limiting conditions, which resulted in a further increase in 3-HP yields revealing values of 21.1 %C-mol and 0.50 g gCDW−1 under phosphate-limiting conditions. The corresponding parameters favoring an increased 3-HP production, i.e. dilution rate as well as C- and P-limiting conditions, were transferred from the small-scale chemostat Cultivation system to 1-L bench-top fermenters operating in fed-batch conditions, revealing 3-HP yields of 15.9 %C-mol and 0.45 g gCDW−1 under C-limiting, as well as 25.6 %C-mol and 0.50 g gCDW−1 under phosphate-limiting conditions. Small-scale chemostat cultures are well suited for the physiological characterization of microorganisms, particularly for investigating the effect of changing Cultivation parameters on microbial performance. In our study, optimal conditions for 3-HP production comprised (i) a low dilution rate of 0.04 h−1 under carbon-limiting conditions and (ii) the use of phosphate-limiting conditions. Similar 3-HP yields were achieved in chemostat and fed-batch cultures under both C- and P-limiting conditions proving the growth rate as robust parameter for process transfer and thus the small-scale chemostat system as powerful tool for process optimization.
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Exploring small-scale chemostats to scale up microbial processes: 3-hydroxypropionic acid production in S. cerevisiae
BMC, 2019Co-Authors: Alicia V. Lis, Konstantin Schneider, Jost Weber, Jay D. Keasling, Michael Krogh Jensen, Tobias KleinAbstract:Abstract Background The physiological characterization of microorganisms provides valuable information for bioprocess development. Chemostat Cultivations are a powerful tool for this purpose, as they allow defined changes to one single parameter at a time, which is most commonly the growth rate. The subsequent establishment of a steady state then permits constant variables enabling the acquisition of reproducible data sets for comparing microbial performance under different conditions. We performed physiological characterizations of a 3-hydroxypropionic acid (3-HP) producing Saccharomyces cerevisiae strain in a miniaturized and parallelized chemostat Cultivation system. The physiological conditions under investigation were various growth rates controlled by different nutrient limitations (C, N, P). Based on the Cultivation parameters obtained subsequent fed-batch Cultivations were designed. Results We report technical advancements of a small-scale chemostat Cultivation system and its applicability for reliable strain screening under different physiological conditions, i.e. varying dilution rates and different substrate limitations (C, N, P). Exploring the performance of an engineered 3-HP producing S. cerevisiae strain under carbon-limiting conditions revealed the highest 3-HP yields per substrate and biomass of 16.6 %C-mol and 0.43 g gCDW−1, respectively, at the lowest set dilution rate of 0.04 h−1. 3-HP production was further optimized by applying N- and P-limiting conditions, which resulted in a further increase in 3-HP yields revealing values of 21.1 %C-mol and 0.50 g gCDW−1 under phosphate-limiting conditions. The corresponding parameters favoring an increased 3-HP production, i.e. dilution rate as well as C- and P-limiting conditions, were transferred from the small-scale chemostat Cultivation system to 1-L bench-top fermenters operating in fed-batch conditions, revealing 3-HP yields of 15.9 %C-mol and 0.45 g gCDW−1 under C-limiting, as well as 25.6 %C-mol and 0.50 g gCDW−1 under phosphate-limiting conditions. Conclusions Small-scale chemostat cultures are well suited for the physiological characterization of microorganisms, particularly for investigating the effect of changing Cultivation parameters on microbial performance. In our study, optimal conditions for 3-HP production comprised (i) a low dilution rate of 0.04 h−1 under carbon-limiting conditions and (ii) the use of phosphate-limiting conditions. Similar 3-HP yields were achieved in chemostat and fed-batch cultures under both C- and P-limiting conditions proving the growth rate as robust parameter for process transfer and thus the small-scale chemostat system as powerful tool for process optimization
