Optimal harvest time

It has been shown that radio frequency impedance (RFI) is an effective tool for moifitoring cell density and cell growth of bioprocesses. The fermentation process, quite complex, is oftentimes difficult to sample and monitor. The RFI measurement could detect cell viability of Escherichia coli during the fermentation, serving as a qualitative measure of the metabolic load of the cell, and thus provide an in situ indicator of the optimal harvesting times. 

Contrary to the previous case, using strategies with low MOTs, cell infection will not be synchronised and the cell population will be distributed over different cell status and different specific infection times (T]) [102], leading to a non-obvious definition of the optimal harvest time, extension of cell lysis and the increase in the proteolytic activity is not easy to predict and account. Although this could be considered a drawback in low MOI strategies, it is possible to control the extension of proteolysis [33,83] by the addition of protease inhibitors. 

Mushroom Species Method of Cultivation Optimal Harvesting Time (Days) Yield of Biomass (g/L) Yield of Chitin or Chitosan (mg/g of Biomass)... 

Borruel and co-workers used EPR spectroscopy to monitor the expresion of holoflavodoxin from cyanobacterium Anabaena PCC 7119 in E. coli It could be shown by EPR, on whole cells frozen in 1 1 glycerol water mixtures, that complete synthesis of the holoprotein takes much longer than that of the apoprotein, and thus the optimal harvest time after induction, 10 hours in this case, could be determined. 

Sato N, Sawada K, Takahashi TA, et al. A time course study for optimal harvest of peripheral blood progenitor cells by granulocyte colony-stimulating factor in healthy volunteers. Exp Hematol 1994 22 973-978. 

There are three major parameters determining the overall product yield and quality of BE VS processes 1) abundance of nutrients 2) timing of baculovirus infection and 3) harvest timing. In considering the state-of-the-art know-how related to these three parameters, we provide a genetic protocol for the rapid determination of optimized BEVS-based process parameters. Optimal parameters for small-scale processes are derived by the following two-step procedure ... 

There are numerous protocols for polysomal gradients preparations that differ mainly at the step for harvesting the cells, and the gradient composition and separation times. The protocol presented later was optimized for isolation of polysomal mRNA from the yeast Saccharomyces cerevisiae, yet many steps will be similar to other eukaryotes and the procedure can easily be modified for other organisms. We will use this protocol as a template on which we will indicate and highlight points that are critical for the microarray analysis. Generally, the RNA isolated by this protocol can be used for analysis by DNA microarray, Northern blot, or RT-PCR. 

Cell inoculum is added to a defined volume of medium in either fermenter or roller bottles, and allowed to grow and Roller bottle be harvested at predetermined optimal time point... 

In a 1991 study by van Reis et al. (5), a filtration operation as applied to harvest of animal cells was optimized by the use of dimensional analysis. The fluid dynamic variables used in the scale-up work were the length of the fibers (L, per stage), the fiber diameter (D), the number of fibers per cartridge (k), the density of the culture (p), and the viscosity of the culture (p). From these variables, scale-up parameters such as wall shear rate (y ) and its effect on flux (L/m /h) were derived. Based on these calculations, an optimum wall shear rate for membrane utilization, operating time, and flux was found. However, because there is no single mathematical expression relating all of these parameters simultaneously, the optimal solution required additional experimental research. 

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