Although drinking can be avoided in many cases, there is still a group of people who work in professions where drinking is necessary. In China alone, there are about 1.3 million people who work as sommeliers. It is a very demanding profession, with an average of 3,000 new wines tasted each year and more than 10,000 flavors stored in the mind. Some high-end sommeliers can take a sip and spit it out when tasting wine. However, this is not possible for white wine. This is because white wine is about the softness of the mouth and the feeling of a line of throat, so it is to be drunk. Although drinking has been a part of their profession, their health is not valued by the society. According to our human practice's survey, some companies don't even buy health insurance for these employees. So our team decided to complete our project with the goal of helping this group of people.

Alcohol,also known as ethanol, has serious harmful effects on the human body by itself. For example, for the nervous system, it can lead to alcoholism, as well as memory loss and, in severe cases, impaired physical movement. In addition to the digestive system, ethanol can cause damage to the gastric mucosa, leading to esophagitis, gastric mucosal erosion, gastric bleeding, gastric perforation, gastritis, and gastric ulcers. Secondly, it can also affect the liver, cardiovascular and cerebrovascular.

When ethanol enters the body, it is converted into acetaldehyde, which is also harmful to the body. Acetaldehyde can enter the body through the respiratory and digestive tracts and can irritate the mucous membranes of the skin, eyes and upper respiratory tract. This eventually leads to coughing, coughing up phlegm, chest tightness, shortness of breath, and even causes the onset of respiratory distress syndrome.

Alcohol is responsible for a large number of deaths, causing more than 300,000 (about 5.3%). Long-term heavy alcohol consumption can significantly increase the incidence of liver cancer, which is 1.5-3 times higher in people who drink alcohol than in the normal population. In China, 2015 statistics show that the overall incidence of liver cancer is 9.4%, and 2018 worldwide statistics show that the overall incidence of liver cancer is 4.8%, which translates to the equivalent of 6.1 liters of pure alcohol per person worldwide. The World Health Organization estimates that alcohol kills 2.5 million people each year, more than AIDS or tuberculosis.

Many of the solutions to alcohol on the internet like drinking yogurt can stick to the intestinal wall to reduce alcohol absorption. This method can reduce the absorption of alcohol to a certain extent, but the effect is relatively limited. There are also a lot of antidotes on the market that are enzymes and will be digested by stomach acid, so they are of little practical use. After further consideration, we chose a probiotic that can colonize the intestinal tract.

We finally chose E.coli Nissle 1917 as our chassis organism. Because probiotics have to enter the human body, it is very necessary to be able to ensure safety. The mechanism of action of EcN lies in its ability to colonize the human intestine and prevent pathogenic bacteria from attacking the intestinal mucosa, which has a protective and repairing effect on the intestinal mucosal barrier. EcN also participates in the immune regulation of the host organism, balancing the secretion of immune factors and enhancing the host's immune capacity, thus alleviating and treating inflammation. These beneficial functions are more or less useful for our project.

At first, our thinking was stuck on how to increase the efficiency of ADH and ALDH, so the designed ideas were always flawed. Later, under the guidance of our teacher, we looked at the degradation process of alcohol from a larger perspective and found that nad+ in the acceleration system was a good breakthrough. Finally, through discussion, our team designed a model. We decided to increase the production of nad+ by increasing the nox enzyme, and as the number of nad+ factors increased, the efficiency of ethanol dehydrogenase and acetaldehyde dehydrogenase increased as well. Eventually the result we hoped for would be achieved: increased conversion of ethanol to acetaldehyde and reduced harm from ethanol and then acetaldehyde to humans.

To better validate our idea, we made two engineered strains: pSB-AA and pSB-AN. For pSB-AA, we only improved its degradation system; while pSB-AN has modified genes in both the acceleration system and the degradation system.

To achieve this effect, we finally chose ethanol dehydrogenase gene, acetaldehyde dehydrogenase gene, NAD+ synthase gene, and NADH oxidase gene. The reason for this is that they control ADH, ALDH, NAD+, and NADH, respectively, and they play crucial roles in both the acceleration and degradation systems.