scholarly journals The metabolic switch can be activated in a recombinant strain of Streptomyces lividans by a low oxygen transfer rate in shake flasks

2018 ◽  
Vol 17 (1) ◽  
Author(s):  
Ramsés A. Gamboa-Suasnavart ◽  
Norma A. Valdez-Cruz ◽  
Gerardo Gaytan-Ortega ◽  
Greta I. Reynoso-Cereceda ◽  
Daniel Cabrera-Santos ◽  
...  
Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2264 ◽  
Author(s):  
Ji-Dong Xu ◽  
Ya-Shuai Niu ◽  
Pan-Pan Yue ◽  
Ya-Jie Hu ◽  
Jing Bian ◽  
...  

Wood auto-hydrolysates (WAH) are obtained in the pulping process by the hydrothermal extraction, which contains lots of hemicelluloses and slight lignin. WAH and chitosan (CS) were introduced into this study to construct WAH-based films by the casting method. The FT-IR results revealed the crosslinking interaction between WAH and CS due to the Millard reaction. The morphology, transmittance, thermal properties and mechanical properties of composite WAH/CS films were investigated. As the results showed, the tensile strength, light transmittances and thermal stability of the WAH-based composite films increased with the increment of WAH/CS content ratio. In addition, the results of oxygen transfer rate (OTR) and water vapor permeability (WVP) suggested that the OTR and WVP values of the films decreased due to the addition of CS. The maximum value of tensile strengths of the composite films achieved 71.2 MPa and the OTR of the films was low as 0.16 cm3·μm·m−2·24 h−1·kPa−1, these properties are better than those of other hemicelluloses composite films. These results suggested that the barrier composite films based on WAH and CS will become attractive in the food packaging application for great mechanical properties, good transmittance and low oxygen transfer rate.


2013 ◽  
Vol 35 (8) ◽  
pp. 1223-1230 ◽  
Author(s):  
Sarah Schiefelbein ◽  
Alexander Fröhlich ◽  
Gernot T. John ◽  
Falco Beutler ◽  
Christoph Wittmann ◽  
...  

Author(s):  
Nina Ihling ◽  
Lara Pauline Munkler ◽  
Christoph Berg ◽  
Britta Reichenbächer ◽  
Johannes Wirth ◽  
...  

Cultivations of mammalian cells are routinely conducted in shake flasks. In contrast to instrumented bioreactors, reliable options for non-invasive, time-resolved monitoring of the culture status in shake flasks are lacking. The Respiration Activity Monitoring Respiration Activity Monitoring System system was used to determine the oxygen transfer rate (OTR) in shake flasks. It was proven that the OTR could be regarded as equal to the oxygen uptake rate as the change of the dissolved oxygen concentration in the liquid phase over time was negligibly small. Thus, monitoring the oxygen transfer rate (OTR) was used to increase the information content from shake flask experiments. The OTR of a Chinese hamster ovary cell line was monitored by applying electrochemical sensors. Glass flasks stoppered with cotton plugs and polycarbonate flasks stoppered with vent-caps were compared in terms of mass transfer characteristics and culture behavior. Similar mass transfer resistances were determined for both sterile closures. The OTR was found to be well reproducible within one experiment (standard deviation <10%). It correlated with changes in cell viability and depletion of carbon sources, thus, giving more profound insights into the cultivation process. Culture behavior in glass and polycarbonate flasks was identical. Monitoring of the OTR was applied to a second culture medium. Media differed in the maximum OTR reached during cultivation and in the time when all carbon sources were depleted. By applying non-invasive, parallelized, time-resolved monitoring of the OTR, the information content and amount of data from shake flask experiments was significantly increased compared to manual sampling and offline analysis. The potential of the technology for early-stage process development was demonstrated.


2017 ◽  
Vol 11 (1) ◽  
Author(s):  
Lena Regestein née Meissner ◽  
Julia Arndt ◽  
Thomas G. Palmen ◽  
Tim Jestel ◽  
Hitoshi Mitsunaga ◽  
...  

2008 ◽  
Vol 7 (3) ◽  
pp. 199-211 ◽  
Author(s):  
Dan Cascaval ◽  
Anca-Irina Galaction ◽  
Stefanica Camarut ◽  
Radu Z. Tudose

1996 ◽  
Vol 34 (3-4) ◽  
pp. 413-420
Author(s):  
Y. C. Liao ◽  
D. J. Lee

Transient model of oxygen transfer rate in a sequencing batch reactor is derived and solved numerically. The dissolved oxygen response under several conditions is analyzed. Effects of operational parameters and liquid bath height are studied. When with short, intermittent aeration periods, the transient effects on oxygen transfer rate may be substantial and should be taken into considerations. An example considering bioreaction is also given.


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