Expanded-bed adsorption is a technique based on fluidiza-tion for recovery of proteins directly from unclarified feedstocks such as fermentation broths, cell homogenates, and other solutions containing suspended particulates. An expanded bed is a chromatography bed with an increased void volume between the adsorbent particles, as compared to a packed chromatography bed. An expanded bed is formed when high-density adsorbent particles are lifted by an upward liquid flow through a column specially designed for expanded bed adsorption. When the bed has expanded and is stable, the particulate-containing feedstock is applied, and the protein of interest can bind to the adsorbent particles while the particulates in the feedstock can pass unhindered through the void of the bed. Expanded-bed adsorption is a one-passage technique designed for large-scale recovery processes. Traditionally, when conventional packed-bed chromatography is used to recover proteins, the feedstock has to be clarified by centrifugation or filtration prior to application or the particulates can block the bed. Expanded-bed adsorption can handle particulate-containing feedstocks; as a result, clarification, concentration, and initial purification are accomplished in one unit operation. Reducing the number of unit operations in a downstream processing scheme decreases the risk of product loss, decreases the processing time, and lowers the overall production costs. The basic principles of expanded-bed adsorption and some applications are described in this article.

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Discover How To Become Your Own Brew Master, With Brew Your Own Beer. It takes more than a recipe to make a great beer. Just using the right ingredients doesn't mean your beer will taste like it was meant to. Most of the time it’s the way a beer is made and served that makes it either an exceptional beer or one that gets dumped into the nearest flower pot.

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