Industrial fermentation
Industrial fermentation is the intentional use of fermentation in manufacturing processes. In addition to the mass production of fermented foods and drinks, industrial fermentation has widespread applications in chemical industry. Commodity chemicals, such as acetic acid, citric acid, and ethanol are made by fermentation.[1] Moreover, nearly all commercially produced industrial enzymes, such as lipase, invertase and rennet, are made by fermentation with genetically modified microbes. In some cases, production of biomass itself is the objective, as is the case for single-cell proteins, baker's yeast, and starter cultures for lactic acid bacteria used in cheesemaking.
In general, fermentations can be divided into four types:[2]
These types are not necessarily disjoined from each other, but provide a framework for understanding the differences in approach. The organisms used are typically microorganisms, particularly bacteria, algae, and fungi, such as yeasts and molds, but industrial fermentation may also involve cell cultures from plants and animals, such as CHO cells and insect cells. Special considerations are required for the specific organisms used in the fermentation, such as the dissolved oxygen level, nutrient levels, and temperature. The rate of fermentation depends on the concentration of microorganisms, cells, cellular components, and enzymes as well as temperature, pH[3] and level of oxygen for aerobic fermentation.[4] Product recovery frequently involves the concentration of the dilute solution.
Production of biomass[edit]
Microbial cells or biomass is sometimes the intended product of fermentation. Examples include single cell protein, bakers yeast, lactobacillus, E. coli, and others. In the case of single-cell protein, algae is grown in large open ponds which allow photosynthesis to occur.[11] If the biomass is to be used for inoculation of other fermentations, care must be taken to prevent mutations from occurring.
Production of intracellular components[edit]
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. Furthermore, the product (typically a protein) must be separated from all of the other cellular proteins in the lysate to be purified.
Precision fermentation[edit]
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.[17] Precision fermentation of genetically modified microorganisms may be used to manufacture proteins needed for cell culture media,[18] providing for serum-free cell culture media in the manufacturing process of cultured meat.[19] A 2021 publication showed that photovoltaic-driven microbial protein production could use 10 times less land for an equivalent amount of protein compared to soybean cultivation.[20]