ABSTRACT
Living cells such as microorganisms and animal cells have been used for many decades for the production of a multitude of products which cover various sectors of application and the application of dierent sectors of biotechnology. e product volume can be very dierent ranging from order of magnitude of 1 kg year-1-1012 kg year-1. e factories where these products are made can be small (e.g., a tabletop factories) to extremely large (containing vessels of 100-30,000 m3). In many fermentation processes, a pure culture of a suitable microorganism is used to produce a desired product. is technology is becoming a major production tool in many dierent application sectors (food, ne-, and bulk chemicals, pharmaceutical). In fermentation processes pure microorganisms or even cells of higher organisms (obtained from plants or certain human or animal tissue) are used to produce a valuable product. e cells themselves are seldom the main product. An exception is e.g., bakers yeast. An important aspect in fermentation processes is the cultivation medium used. In many cases undened media are used, oen containing waste material from e.g., the sugar industry (cane or beet molasses), cheese manufacturing (wey), wet milling of maize (corn steep liquor), and other ingredients like soybean meal, vegetable oils, yeast extract, etc. e advantage of these complex or undened media is that they are relatively cheap which is an important factor in fermentation processes because the cultivation medium can be a signi- cant cost factor. e disadvantage is that the exact composition of the ingredients of complex media is oen not known, while dierences in composition may occur between dierent batches. is hampers careful attempts to optimize the fermentation process in order to increase the productivity and yield of the desired product. For this reason several industries have made the decision to switch to dened cultivation media for certain fermentation processes. e composition of dened cultivation media can be very dierent and is highly dependent on the applied microorganism or cell culture used, the way the process is operated, and the desired product to be produced. A good starting point for the design of a cultivation medium for a certain process is to analyze the biochemical composition of the microorganism or cell culture which will be applied and which components have to be supplied to the medium
because the cells are not able to synthesize these themselves, e.g., amino acids, vitamins, etc. In many cases dened media for the cultivation of microorganisms, but also for plant cells contain relatively few compounds (in the order of tens), whereas dened media for the cultivation of animal cells may contain up to hundreds of dierent compounds. It should be realized that such complicated media are much more expensive than the more simple media.
