Upstream Processing

Upstream processing comprises tasks in the initial stages of the fermentation process in biotechnology. This includes all steps related to the development of microorganisms, nutrient preparation, cell culture, cell separation and harvesting. As soon as the cells/bacteria have reached the desired density, they are harvested and moved to the subsequent bioprocess, the downstream processing, where they are further processed.

Upstream processing involves nutrient preparation. Like humans, cells in a culture also need the right nutrition to function and to produce the intended value product. The nutrients consist predominantly of different components, such as carbohydrates (glucose), nitrogen (amino acids), fats (lipids) and trace amounts of salt. The ingredients are mostly in powder form and are dissolved in high purity water. It is essential that the components are well mixed. The mixed solution is then fed to the fermenter.

The next step is the cell cultivation. Cells are growing and multiplied in a suitable environment. This is ideally composed of nutrients for growth and cell culture vessels for controlling gases and temperature.

The last step is cell separation, or cell harvesting. This is done first often by centrifugation. Here, the cells separate from the culture by the centrifugal forces generated and sediment. The subsequent filtration steps remove the main impurities from the harvest. Finally, diaphragm filtration and sterile-grade filtration ensure that even minor and microbial contaminations are removed.