Determining Complete Suspension of Immobilized Enzymes by Analysis of Digital Camera Images

Eberhard, Werner; Jäger, Gernot; Pinto, João P. C.; Spieß, Antje C.; Büchs, Jochen

doi:10.1080/00986445.2011.592552

Cited by 3 publications

(1 citation statement)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…toluene should improve the immobilizate's suspension by minimizing the density difference between particles and solvent. This will decrease the energy input into the system necessary for complete suspension [25]…”

Section: Scattering Of Pva-hydrogels Affects Dlr-based Ph-measurementmentioning

confidence: 99%

Dual lifetime referencing enables pH‐control for oxidoreductions in hydrogel‐stabilized biphasic reaction systems

Begemann

Spieß

2015

Biotechnology Journal

Self Cite

View full text Add to dashboard Cite

pH-shifts are a serious challenge in cofactor dependent biocatalytic oxidoreductions. Therefore, a pH control strategy was developed for reaction systems, where the pH value is not directly measurable. Such a reaction system is the biphasic aqueous-organic reaction system, where the oxidoreduction of hydrophobic substrates in organic solvents is catalysed by hydrogel-immobilized enzymes, and enzyme-coupled cofactor regeneration is accomplished via formate dehydrogenase, leading to a pH-shift. Dual lifetime referencing (DLR), a fluorescence spectroscopic method, was applied for online-monitoring of the pH-value within the immobilizates during the reaction, allowing for a controlled dosage of formic acid. It could be shown that by applying trisodium 8-hydroxypyrene-1, 3, 6-trisulfonate as pH indicator and Ru(II) tris(4, 7-diphenyl-1, 10-phenantroline) (Ru[dpp]) as a reference luminophore the control of the pH-value in a macroscopic gel-bead-stabilized aqueous/organic two phase system in a range of pH 6.5 to 8.0 is possible. An experimental proof of concept could maintain a stable pH of 7.5 ± 0.15 during the reaction for at least 105 h. With these results, it could be shown that DLR is a powerful tool for pH-control within reaction systems with no direct access for conventional pH-measurement.

show abstract

Section: Scattering Of Pva-hydrogels Affects Dlr-based Ph-measurementmentioning

confidence: 99%

Dual lifetime referencing enables pH‐control for oxidoreductions in hydrogel‐stabilized biphasic reaction systems

Begemann

Spieß

2015

Biotechnology Journal

Self Cite

View full text Add to dashboard Cite

show abstract

Assessment of air entrainment in stirred tanks using capacitive sensors

Zou

Yang

Zhan

et al. 2014

Sensors and Actuators A: Physical

View full text Add to dashboard Cite

Black glucose-releasing silicon elastomer rings for fed-batch operation allow measurement of the oxygen transfer rate from the top and optical signals from the bottom for each well of a microtiter plate

et al. 2023

View full text Add to dashboard Cite

Background In industrial microbial biotechnology, fed-batch processes are frequently used to avoid undesirable biological phenomena, such as substrate inhibition or overflow metabolism. For targeted process development, fed-batch options for small scale and high throughput are needed. One commercially available fed-batch fermentation system is the FeedPlate®, a microtiter plate (MTP) with a polymer-based controlled release system. Despite standardisation and easy incorporation into existing MTP handling systems, FeedPlates® cannot be used with online monitoring systems that measure optically through the transparent bottom of the plate. One such system that is broadly used in biotechnological laboratories, is the commercial BioLector. To allow for BioLector measurements, while applying the polymer-based feeding technology, positioning of polymer rings instead of polymer disks at the bottom of the well has been proposed. This strategy has a drawback: measurement requires an adjustment of the software settings of the BioLector device. This adjustment modifies the measuring position relative to the wells, so that the light path is no longer blocked by the polymer ring, but, traverses through the inner hole of the ring. This study aimed at overcoming that obstacle and allowing for measurement of fed-batch cultivations using a commercial BioLector without adjustment of the relative measurement position within each well. Results Different polymer ring heights, colours and positions in the wells were investigated for their influence on maximum oxygen transfer capacity, mixing time and scattered light measurement. Several configurations of black polymer rings were identified that allow measurement in an unmodified, commercial BioLector, comparable to wells without rings. Fed-batch experiments with black polymer rings with two model organisms, E. coli and H. polymorpha, were conducted. The identified ring configurations allowed for successful cultivations, measuring the oxygen transfer rate and dissolved oxygen tension, pH, scattered light and fluorescence. Using the obtained online data, glucose release rates of 0.36 to 0.44 mg/h could be determined. They are comparable to formerly published data of the polymer matrix. Conclusion The final ring configurations allow for measurements of microbial fed-batch cultivations using a commercial BioLector without requiring adjustments of the instrumental measurement setup. Different ring configurations achieve similar glucose release rates. Measurements from above and below the plate are possible and comparable to measurements of wells without polymer rings. This technology enables the generation of a comprehensive process understanding and target-oriented process development for industrial fed-batch processes.

show abstract

Determining Complete Suspension of Immobilized Enzymes by Analysis of Digital Camera Images

Cited by 3 publications

References 25 publications

Dual lifetime referencing enables pH‐control for oxidoreductions in hydrogel‐stabilized biphasic reaction systems

Dual lifetime referencing enables pH‐control for oxidoreductions in hydrogel‐stabilized biphasic reaction systems

Assessment of air entrainment in stirred tanks using capacitive sensors

Black glucose-releasing silicon elastomer rings for fed-batch operation allow measurement of the oxygen transfer rate from the top and optical signals from the bottom for each well of a microtiter plate

Contact Info

Product

Resources

About