1,721,167 research outputs found
INDIRECT ESTIMATION OF CELL MASS AND SUBSTRATE CONCENTRATION USING A COMPUTER-COUPLED MASS-SPECTROMETER
No full textOn-line estimation of cell mass and substrate concentration based on exhaust gas analysis was developed. The O-2, CO2, H2O, and N-2 contents at the inlet and outlet of fermenter, analyzed by a computer-coupled quadrupole mass spectrometer, were used to calculate the oxygen uptake rate and carbon dioxide evolution rate, and these rates were further used to evaluate cell mass and substrate concentration in a recombinant Escherichia coli fermentation. Cell mass, glucose concentration, specific growth rate, and specific consumption rate of glucose were well estimated by this method; the oxygen uptake rate gave more accurate estimates for these state variables than did the carbon dioxide evolution rate
Quantitative Analysis of Metabolic Activities During Cloned Gene Expression using Mass Spectromerer
No full textEFFECT OF STRESS FREQUENCY ON THE CYCLIC CREEP-BEHAVIOR OF ZIRCALOY-4 IN THE DYNAMIC STRAIN AGING TEMPERATURE-RANGE
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FORMATION OF PHOSPHIDES IN P-DOPED 304L STAINLESS-STEEL
No full textThe precipitation of phosphide and the orientation relationship with the austenitic matrix in P-doped 304L stainless steel have been studied in detail using transmission electron microscopy and computer-simulated stereographic projection. The M3P phosphide was identified in aged samples and confirmed by computer simulation of selected area diffraction patterns. The needle-shaped phosphide is randomly distributed in the austenitic matrix, and grows into thin laths on <001>M austenite planes
Optimization of feeding strategy for overproduction of human lipocortin-I in Saccharomyces cerevisiae controlled by the GAL10 promoter
No full textFed-batch fermentation was conducted to overproduce human lipocortin-1 (LC1) in recombinant Saccharomyces cerevisiae controlled by the GAL10 promoter. To optimize the feeding strategy, various fed-batch culture modes were performed with concentrated feed media containing carbon mixtures of galactose (Gal) and glucose (Glu) at three different concentration ratios (Gal:Glu ratios): 9:1, 1:1, 1:9. The cell growth, expression level of LC1, and the plasmid stability were investigated under these fed-batch culture modes, While both glucose and galactose were being fed to the fermenter, the glucose concentration in the culture broth was kept below 1 g/l for efficient gene expression. High cell concentrations of greater than 100 g dry cell weight/l mere achieved with these fed-batch culture modes. A significant amount of intact LC1 was found to be secreted into the culture medium, but proteolytically cleaved products (des1-26-LC1) were also observed in the culture medium. The fed-batch fermentation with the feed medium at a Gal: Glu ratio of 1:1 resulted in the highest LC1 total (intact LC1+des1-26-LC1) concentration of 500 mg/l, which corresponded to 1.73- and 1.83-fold increases over that produced with the media at Gal: Glu ratios of 1:9 and 9:1, respectively
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