1 OVERVIEW OF BIOSEPARATIONS  Bioseparations are elaborate and expensive.  Up to 90% of new product cost is in downstream processing.  More than 60% of the cost of third and fourth generation antibiotics is in purification.  For recombinant DNA fermentation products, downstream processing can account for 80 to 90% of the overall processing cost.  Bioproducts—chemical substances or combinations of chemical substances that are made by living things  They are sold for their chemical activity.

2  To improve the design of bioseparations, the following questions should be answered: (1)What is the value of the product? (2)What is an acceptable product quality? (3)Where is the product in each process stream? (4)Where are the impurities in each process stream? (5)What are the unusual physicochemical properties of the product and the principal impurities? (6)What are the economics of various alternative separations?

3 * An inverse relationship between price and production: (果膠酶，果汁業用) (毛地黃，自植物葉子提煉，強心劑) (紫杉醇，殺乳癌細胞) (紅血球生成素) (生物鹼，長春花提煉，腫瘤抑制劑)

4 *Different levels of purity are required for different products:

5  Bioproducts can be broadly classified into three categories: small molecules, large molecules, and particulate products.  There are three corresponding separation procedures for purifying them.

6 (1) Separation of insolubles *Objectives: remove or collect cells, cell debris, or other particulates *Typical operations: filtration, centrifugation *Relatively little product concentration or improvement of product quality occurs.  Most bioseparations have four similar steps:

7  Most bioseparations have four similar steps (2/3): (1) Separation of insolubles (2) Isolation of products *Objectives: remove materials of widely divergent properties compared to the desired product *Typical operations: extraction, adsorption, ultrafiltration, precipitation *Appreciable concentration and product quality increases usually occur.

8  Most bioseparations have four similar steps (3/3): (1) Separation of insolubles (2) Isolation of products (3) Purification *Objectives: remove impurities of similar chemical functionality and physical properties *Typical operations: chromatography, affinity methods, fractional precipitation, electrophoresis (4) Polishing *Objectives: remove liquids *Typical operations: drying, crystallization (not always possible)

9  Processing profile of antibiotics: Product StepTypical ProcessConc. (g/L) Quality (%) Harvest broth Fermentation Separation of insolubles Filtration IsolationExtraction PurificationChromatography PolishingCrystallization

10  Separation principles used in various recovery steps:

11 Extracellular Product

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13 Process for ethanol production from fermentation:

14 Manufacture of citric acid:

15 Penicillin production:

16  Production of an intracellular enzyme:

17  Processing scheme for recombinant insulin: (Inclusion Body)

18  Processing scheme for recombinant insulin (2/2):

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