Background
It is common knowledge to us that E. coli is very useful biologically, but not to those who are not interested in biology. We wanted to make E. coli a bacterium that people would like. So we thought about what kind of bacteria are generally liked. Bacteria generally have a bad image, such as illness, but there are bacteria that have a good image. These are the bacteria used in food fermentation. By incorporating the major enzymes of these bacteria into E. coli, we thought we could give E. coli a good image. Among the bacteria used for fermentation, yeast, acetic acid, and lactic acid bacteria have been of great benefit to us, so we decided to use these bacteria.
Yeast is mainly used in the production of bread, and their main function is thought to be the emission of carbon dioxide. E. coli is a commensal anaerobe and emits carbon dioxide. However, E. coli produces formic acid in the pyruvate circuit. Therefore, we thought of inhibiting pyruvate formate lyase, the enzyme that produces formic acid, with an antisense chain.
Lactobacillus produce cheese and other products using L-lactic acid obtained in the kori circuit. E. coli also produces lactic acid in the same way, but reversibly converts lactic acid back to pyruvate in the kori circuit. Therefore, we thought that by incorporating the antisense chain of histidinol dehydrogenase, it would be able to produce more L-lactic acid, which would have the same function as lactic acid bacteria.
Acetobacter is used in the production of vinegar, and perform acetic acid fermentation to expel acetic acid from alcohol. Since E. coli cannot grow in the presence of alcohol, we wanted to use the pathway that produces acetic acid from acetyl coA. However, since acetyl coA is also used in the TCA circuit, we incorporated the antisense chain of citrate synthase. By doing so, we thought that acetyl coA, which is converted to citric acid, would be converted to acetic acid and thus be able to produce vinegar.
This will make E. coli capable of producing a variety of fermented foods and improve people's image of E. coli.