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Downstream processing
About: Downstream processing is a research topic. Over the lifetime, 781 publications have been published within this topic receiving 18366 citations.
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TL;DR: This tutorial review the focus is set on the evaluation of immobilized enzymes in respect to mass transport limitations, immobilization yield and stability, to enable industrial applications.
Abstract: In contrast to the application of soluble enzymes in industry, immobilized enzymes often offer advantages in view of stability, volume specific biocatalyst loading, recyclability as well as simplified downstream processing. In this tutorial review the focus is set on the evaluation of immobilized enzymes in respect to mass transport limitations, immobilization yield and stability, to enable industrial applications.
525 citations
TL;DR: A series of large-scale applications of immobilized enzymes with benefits for the food, chemical, pharmaceutical, cosmetics and medical device industries, some of which have been scarcely reported on previously are presented.
427 citations
TL;DR: Alkaline proteases useful for detergent applications are mostly active in the pH range 8–12 and at temperatures between 50 and 70°C, with a few exceptions of extreme pH optima up to pH 13 and activity at temperatures up to 80–90°C.
Abstract: Microbial alkaline proteases dominate the worldwide enzyme market, accounting for a two-thirds share of the detergent industry. Although protease production is an inherent property of all organisms, only those microbes that produce a substantial amount of extracellular protease have been exploited commercially. Of these, strains of Bacillus sp. dominate the industrial sector. To develop an efficient enzyme-based process for the industry, prior knowledge of various fermentation parameters, purification strategies and properties of the biocatalyst is of utmost importance. Besides these, the method of measurement of proteolytic potential, the selection of the substrate and the assay protocol depends upon the ultimate industrial application. A large array of assay protocols are available in the literature; however, with the predominance of molecular approaches for the generation of better biocatalysts, the search for newer substrates and assay protocols that can be conducted at micro/nano-scale are becoming important. Fermentation of proteases is regulated by varying the C/N ratio and can be scaled-up using fed-batch, continuous or chemostat approaches by prolonging the stationary phase of the culture. The conventional purification strategy employed, involving e.g., concentration, chromatographic steps, or aqueous two-phase systems, depends on the properties of the protease in question. Alkaline proteases useful for detergent applications are mostly active in the pH range 8–12 and at temperatures between 50 and 70°C, with a few exceptions of extreme pH optima up to pH 13 and activity at temperatures up to 80–90°C. Alkaline proteases mostly have their isoelectric points near to their pH optimum in the range of 8–11. Several industrially important proteases have been subjected to crystallization to extensively study their molecular homology and three-dimensional structures.
399 citations
TL;DR: It is argued that separation technologies such as aqueous two-phase extraction with short chain alcohols, pervaporation, reverse osmosis, and in situ extractive or pervaporative fermentations deserve more attention in the future.
Abstract: 1,3-Propanediol and 2,3-butanediol are two promising chemicals which have a wide range of applications and can be biologically produced. The separation of these diols from fermentation broth makes more than 50% of the total costs in their microbial production. This review summarizes the present state of methods studied for the recovery and purification of biologically produced diols, with particular emphasis on 1,3-propoanediol. Previous studies on the separation of 1,3-propanediol primarily include evaporation, distillation, membrane filtration, pervaporation, ion exchange chromatography, liquid-liquid extraction, and reactive extraction. Main methods for the recovery of 2,3-butanediol include steam stripping, pervaporation, and solvent extraction. No single method has proved to be simple and efficient, and improvements are especially needed with regard to yield, purity, and energy consumption. Perspectives for an improved downstream processing of biologically produced diols, especially 1,3-propanediol are discussed based on our own experience and recent work. It is argued that separation technologies such as aqueous two-phase extraction with short chain alcohols, pervaporation, reverse osmosis, and in situ extractive or pervaporative fermentations deserve more attention in the future.
358 citations
TL;DR: Adsorption in stable expanded beds enables proteins to be recovered directly from particulate-containing feedstocks, such as fermentation broths and preparations of disrupted cells, without the need for prior removal of the suspended solids, which would normally result in the blockage of packed beds.
335 citations