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Chapter 46 : Raw Materials Selection and Medium Development for Industrial Fermentation Processes
This chapter focuses primarily on raw materials and medium development for microbial fermentation processes. Chemically defined media have been used routinely in the laboratory to study the microbial biosynthesis of primary and secondary metabolites. Today, most fermentation processes employ complex media. However, chemically defined media are becoming popular where process consistency is very important, such as the production of biologics. When the chemically defined medium was compared with the initial, optimized complex medium for producing the secondary metabolite by Streptomyces, the chemically defined medium reduced the medium cost by 4.5-fold and increased the titer by 80% at the 800-liter scale. Glucose is the most frequently used carbohydrate in the fermentation industry. The white crystalline sucrose is generally used in small-scale applications and in seed fermentors. Other sugars that are used less frequently in the fermentation industry include maltose, mannitol, sorbitol, and xylose. Oils can supply both the energy and the growth carbon needs of the organism. The most important oil in the U.S. fermentation industry is soybean oil. The sources derived from agricultural products are the workhorse ingredients of the fermentation industry. They include the products of commodities such as various grains and soybean. The soybean flours, meals, and grits head the list of applications in antibiotic fermentations. Metal-chelating agents such as EDTA are often included in fermentation media. Crude preparations of enzymes such as amylase, protease, and cellulase are used to precondition the medium. Invariably, these enzymes are used at the mixing stage before medium sterilization.