Modeling and Applications of Downstream Processing

Abstract

Downstream processing is playing an increasingly important role in the biochemical industry, especially since the advent of recombinant DNA technology. The use of recombinant DNA technology not only enables improvements in the production efficiency of therapeutic and industrial proteins, but it also permits the modification and improvement of protein structure and thus function.However, the commercial application of such technology was initially accompanied by concerns over product safety.Quality criteria have been made especially stringent for products derived from genetically-modified microorganisms. The establishment of strict quality guidelines was the result of early concern about the oncogenic potential related to products contaminated by DNA sequences of the host mammalian cells (1). The quest for high quality has created a growing need for high-resolution techniques at the process scale as well as for novel strategies for the isolation and purification of bioproducts. Since the typical environment for producing biologicals is a complex one and quality criteria need to be strict, primary recovery techniques are typically implemented in a purification scheme prior to (or in conjunction with) high-resolution techniques. The most sophisticated and useful schemes take advantage of both the different physical and chemical properties of the components in complex mixtures and of the interactive nature of the downstream processing techniques (see Figure 1).

Cell clarification and size separation using continuous countercurrent magnetophoresis

“…For this reason, membrane filtration is commonly used for the separation of whole cells from fermentation fluid where the biological product of interest is produced extracellularly, whereas centrifugation is preferred for the separation of cell debris after lysing the cells to release intracellularly produced inclusion bodies. 5, 7 Capital costs for membrane filtration are also high; however, membrane filtration offers lower maintenance and operating costs than does centrifugation. 4…”

Separation of enzymes from microorganism crude extracts by free-flow zone electrophoresis

“…Recently, by comparison of Here we explore the correlation between free-flow zone electrophoresis and the electrophoretic titration curve of a mixture of proteins. The analytical electrophoretic titration curve provides net charge vs. pH information over a wide pH range (3)(4)(5)(6)(7)(8)(9) within a few hours. We also note here that, among the crude extract enzymes separated, the methanol oxidase has too high a molecular weight (>6oO,OoO) and interferes with the gel matrix and with the other enzymes applied onto the gel.…”

Preparation of Silica@Silica Core–Shell Microspheres Using an Aqueous Two-Phase System in a Novel Microchannel Device

“…Aqueous two-phase system (ATPS) as a liquid−liquid fractionation technique has attracted research interests since it was discovered by Beijerinck in 1896. 1 Briefly, a phase interface occurs in a uniform system to form two-phase incompatible aqueous solutions from a homogeneous aqueous solution containing two incompatible polymers or a polymer and an inorganic salt when the concentration of the polymer reaches a certain value. Wessleén and Albertsson developed a two-phase extraction method using ATPS to concentrate animal viruses, which is probably the first practical application of ATPS.…”