Cell-protein fouling

This review is included to provide some context for the work described below. It briefly examines protein fouling, cell-protein fouling and membrane cleaning. 

For suspensions of particles with sizes nearer to the pore size, some internal pore fouling will occur but at a greatly reduced rate. Figure 2.4122 shows cross-flow filtration of a single cell protein suspension on a "tortuous-pore" membrane. The flux declines rapidly at first, as boundary layer conditions are established, and then levels off with a diminishing rate of flux decay. 

Fermentation Processes. The efficient production of penicillin, yeasts, and single-celled protein by fermentation requires defoamers to control gas evolution dnring the reaction. Animal fats snch as lard [61789-99-9] were formerly used as a combined defoamer and nntrient, but now more effective proprietary prod-nets are nsnally employed. Defoamer application technology has also improved. For example, in modern yeast production facilities, the defoamers are introduced by means of antomatic electrode-activated devices. One concern in the use of defoamers in fermentation processes is the potential fouling of membranes during downstream Ultrafiltration. Silicone antifoams (42) seem less troubled by this problem than other materials. 

Cell-free translation system, used for the identification of cloned genes and gene expression, has been investigated extensively as a preparative production system of commercially interesting proteins after the development of continuous-flow cell-free translation system. Many efforts have been devoted to improve the productivity of cell-free system [1], but the relatively low productivity of cell-free translation system still limits its potential as an alternative to the protein production using recombinant cells. One approach to enhance the translational efficiency is to use a condensed cell-free translation extract. However, simple addition of a condensed extract to a continuous-flow cell-free system equipped with an ultrafiltration membrane can cause fouling. Therefore, it needs to be developed a selective condensation of cell-free extract for the improvement of translational efficiency without fouling problem. 

Another attractive application of polymer brushes is directed toward a biointerface to tune the interaction of solid surfaces with biologically important materials such as proteins and biological cells. For example, it is important to prevent surface adsorption of proteins through nonspecific interactions, because the adsorbed protein often triggers a bio-fouling, e.g., the deposition of biological cells, bacteria and so on. In an effort to understand the process of protein adsorption, the interaction between proteins and brush surfaces has been modeled like the interaction with particles, the interaction with proteins is simplified into three generic modes. One is the primary adsorption. 

Both the concentration-polarization layer and membrane fouling are present (filtration in presence of macromolecules, proteins, cells in the liquid phase). 

External fouling is caused by the formation of a cake layer of cells or other materials on the membrane surface, leading to a reduction in permeate flux (defined as the volume of permeate produced per time and membrane area). Internal fouling is caused mainly by proteins and particles smaller than membrane pores. Proteins and protein aggregates can adsorb or deposit at the pore entrance or inside the pores and cause pore blockage or narrowing, leading to increased hydraulic resistance (2). 

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