Industrial fermentation
[1] Moreover, nearly all commercially produced industrial enzymes, such as lipase, invertase and rennet, are made by fermentation with genetically modified microbes.
For instance, to avoid biological process contamination, the fermentation medium, air, and equipment are sterilized.
It is generally not possible to take fermentation conditions that have worked in the laboratory and blindly apply them to industrial scale equipment.
Although many parameters have been tested for use as scale up criteria, there is no general formula because of the variation in fermentation processes.
If all of the nutrients in the medium are consumed, or if the concentration of toxins is too great, the cells may become senescent and begin to die off.
More sensitive fermentations may instead use purified glucose, sucrose, glycerol or other sugars, which reduces variation and helps ensure the purity of the final product.
[citation needed] Fixed nitrogen sources are required for most organisms to synthesize proteins, nucleic acids and other cellular components.
Depending on the enzyme capabilities of the organism, nitrogen may be provided as bulk protein, such as soy meal; as pre-digested polypeptides, such as peptone or tryptone; or as ammonia or nitrate salts.
The amount of phosphate which must be added depends upon the composition of the broth and the needs of the organism, as well as the objective of the fermentation.
[9] Growth factors and trace nutrients are included in the fermentation broth for organisms incapable of producing all of the vitamins they require.
Inorganic nutrients, including trace elements such as iron, zinc, copper, manganese, molybdenum, and cobalt are typically present in unrefined carbon and nitrogen sources, but may have to be added when purified carbon and nitrogen sources are used.
This involves replacing the nitrogen and carbon sources that show an enhancement effect on the intended production.
In the case of single-cell protein, algae is grown in large open ponds which allow photosynthesis to occur.
Secondary metabolites are compounds made in the stationary phase; penicillin, for instance, prevents the growth of bacteria which could compete with Penicillium molds for resources.
These compounds are of obvious value to humans wishing to prevent the growth of bacteria, either as antibiotics or as antiseptics (such as gramicidin S).
[13] Of primary interest among the intracellular components are microbial enzymes: catalase, amylase, protease, pectinase, cellulase, hemicellulase, lipase, lactase, streptokinase and many others.
[14] Recombinant proteins, such as insulin, hepatitis B vaccine, interferon, granulocyte colony-stimulating factor, streptokinase and others are also made this way.
[6] The largest difference between this process and the others is that the cells must be ruptured (lysed) at the end of fermentation, and the environment must be manipulated to maximize the amount of the product.
Common crops such as sugar cane, potato, cassava, and maize are fermented by yeast to produce ethanol which is further processed to become fuel.
Fungi have been employed to break down cellulosic wastes to increase protein content and improve in vitro digestibility.
[16] Precision fermentation is an approach to manufacturing specific functional products which intends to minimise the production of unwanted by-products through the application of synthetic biology, particularly by generating synthetic "cell factories" with engineered genomes and metabolic pathways optimised to produce the desired compounds as efficiently as possible with the available resources.
