A cultivation strategy combining the advantages of temperature-limited fed-batch and probing feeding control is presented. The technique was evaluated in fed-batch cultivations with E. coli BL21(DE3) producing xylanase in a 3 liter... more
A cultivation strategy combining the advantages of temperature-limited fed-batch and probing feeding control is presented. The technique was evaluated in fed-batch cultivations with E. coli BL21(DE3) producing xylanase in a 3 liter bioreactor. A 20% increase in cell mass was achieved and the usual decrease in specific enzyme activity normally observed during the late production phase was diminished with the new technique. The method was further tested by growing E. coli W3110 in a larger bioreactor (50 l). It is a suitable cultivation technique when the O2 transfer capacity of the reactor is reached and it is desired to continue to produce the recombinant protein.
Vascular endothelial growth factor (VEGF(165)) is a potent mitogen that induces angiogenesis and vascular permeability in vivo and has demonstrated potential in therapeutic applications for accelerating wound healing. An industrial... more
Vascular endothelial growth factor (VEGF(165)) is a potent mitogen that induces angiogenesis and vascular permeability in vivo and has demonstrated potential in therapeutic applications for accelerating wound healing. An industrial production method that provides high yield as well as high purity, quality, and potency is needed. The process described in this report involves a bacterial expression system capable of producing approximately 9g of rhVEGF per liter of broth and a downstream purification process consisting of protein refolding and three chromatography steps prior to formulation of the drug substance. A high cell density (HCD) fed-batch fermentation process was used to produce rhVEGF in periplasmic inclusion bodies. The inclusion bodies are harvested from the cell lysate and subjected to a single-step protein solubilization and refolding operation to extract the rhVEGF for purification. Overall recovery yields observed during development, including refolding and chromatography, were 30+/-6%. Host cell impurities are consistently cleared below target levels at both laboratory and large-scale demonstrating process robustness. The structure of the refolded and purified rhVEGF was confirmed by mass spectrometry, N-terminal sequencing, and tryptic peptide mapping while product variants were analyzed by multiple HPLC assays. Biological activity was verified by the proliferation of human umbilical vein derived endothelial cells.
This report describes the building of a simulator for prediction of the dissolved oxygen concentration, the oxygen transfer rate and the concentration of carbon dioxide in a fermentation process. The steady state models were made using... more
This report describes the building of a simulator for prediction of the dissolved oxygen concentration, the oxygen transfer rate and the concentration of carbon dioxide in a fermentation process. The steady state models were made using the linguistic equations method. The dynamic models were made using Simulink® toolbox in the Matlab®. At the beginning, some basics about fermentation and microbiological
... of the C source has been pointed out in several recent optimization studies ... pre treatment of wheat straw used as the inducing substrate for xylanase production by T ... Organism Substrate Cultivation conditions Xylanase Cellulase... more
... of the C source has been pointed out in several recent optimization studies ... pre treatment of wheat straw used as the inducing substrate for xylanase production by T ... Organism Substrate Cultivation conditions Xylanase Cellulase Activity", Productb, Assay' FPase't, CMCa", IU ml IU ...
In order to improve the production of human-like collagen III (HLC III) by fed-batch culture of recombinant Escherichia coli BL21, the Plackett-Burman and Box-Behnken design were applied to optimize the fermentation process parameters.... more
In order to improve the production of human-like collagen III (HLC III) by fed-batch culture of recombinant Escherichia coli BL21, the Plackett-Burman and Box-Behnken design were applied to optimize the fermentation process parameters. Three variables (induction time, inoculum age and pH), which have significant effects on HLC III production, were selected from eight variables by Plackett-Burman design. With the regression coefficient analysis in the Box-Behnken design, a relationship between HLC III production and three significant factors was obtained, and the optimum levels of the three variables were as follows: induction time 3.2h, inoculum age 12.6 h and pH 6.7. The 3D response surface plots and 2D contour plots created by the Box-Behnken design showed that the interaction between induction time and pH and that between innoculum age and pH were significant. An average 9.68 g·L−1HLC III production was attained in the validation experiment under optimized condition, which was 80% higher than the yield of 5.36 g·L−1 before optimization.
Biotechnology process development involves strain testing and improvement steps aimed at increasing yields and productivity. This necessitates the high-throughput screening of many potential strain candidates, a task currently mainly... more
Biotechnology process development involves strain testing and improvement steps aimed at increasing yields and productivity. This necessitates the high-throughput screening of many potential strain candidates, a task currently mainly performed in shake flasks or microtiter plates. However, these methods have some drawbacks, such as the low data density (usually only end-point measurements) and the lack of control over cultivation conditions in standard shake flasks. Microbioreactors can offer the flexibility and controllability of bench-scale reactors and thus deliver results that are more comparable to large-scale fermentations, but with the additional advantages of small size, availability of online cultivation data and the potential for automation. Current microbioreactor technology is analyzed in this review paper, focusing on its industrial applicability, and directions for future research are presented.
... The changes in macroscopic properties also induce a modification of cell physiology and biochemical reactions, provoking several chemical alterations in the tissue such as changes in the volatile profile (Chiralt et al., 2001), or... more
... The changes in macroscopic properties also induce a modification of cell physiology and biochemical reactions, provoking several chemical alterations in the tissue such as changes in the volatile profile (Chiralt et al., 2001), or developments of chemicals (ie ethanol or ...
In this paper a short overview is given of the several FET-based sensor devices and the operational principle of the ISFET is summarized. Some of the shortcomings of the FET sensors were circumvented by an alternative operational mode,... more
In this paper a short overview is given of the several FET-based sensor devices and the operational principle of the ISFET is summarized. Some of the shortcomings of the FET sensors were circumvented by an alternative operational mode, resulting in a device capable of acid/base concentration determination by coulometric titrant generation as well as in an original pH-static enzyme sensor.
Hydrogen production plays a very important role in the development of hydrogen economy. One of the promising hydrogen production approaches is conversion from biomass, which is abundant, clean and renewable. Alternative thermochemical... more
Hydrogen production plays a very important role in the development of hydrogen economy. One of the promising hydrogen production approaches is conversion from biomass, which is abundant, clean and renewable. Alternative thermochemical (pyrolysis and gasification) and biological (biophotolysis, water–gas shift reaction and fermentation) processes can be practically applied to produce hydrogen. This paper gives an overview of these technologies for hydrogen production from biomass. The future development will also be addressed.
