Team:SDSZ China/Integrated Practices

© 2016 SDSZ_China iGEM
Test What You Can't TASTE

Research and Outreach

We want to know whether our competitive binding reaction test is valuable to the milk quality control. In order to do that, we need to understand the overall situation of antibiotic residue in the country and with respect to the whole world, so we approached to Dr. Lu Meng in the Chinese Academy of Agricultural Science, hoping that she could introduce us to the bigger picture, and how our idea fit into the picture. 

Q: Can you briefly inform us how much milk in the world is contaminated by over-the-limit antibiotic residues?

A: According to an FDA report in March, 2015, 15 milk samples out of the total 1918 was tested positive for 16 types of excessive antibiotics, and a EU report in 2014 shows that 35 out of 29533 milk samples collected from its 28 member countries contain antibiotics that are higher than the MRLs. They both tell us that the antibiotic residues in milk is a problem faced by the whole world.

Q: What are the aspects that we need to focus on when developing our project to detect antibiotics in milk?

A: The current ways of testing either has deficiencies in sensitivity, or costs too much to be popularized and utilized in all part of the country. So if you guys can lower the price of the method to a certain extent that individual diary farmers can purchase and run the test before the milk is delivered anywhere else, the unqualified milk with excessive amount of antibiotics will be stopped from going out. This improvement could be significant in China because there are a lot of rural areas where “Milk Bars” are the customers main source of milk. Milk from the "Milk Bar" is claimed to be fresher than those produced by big processing companies like Yili or Mengniu, but the fact that they are directly transported from diary farms doesn’t mean they are more healthy. They skip the quality inspection done by those companies and the only process they go through is pasteurization, and there is no way to know if they contain high amount of antibiotic residues. 

Q: Do dairy farms take any actions to prevent leaving excessive amount of antibiotics in milk?

A: Of course they do. Farms and ranches should behave according to the China Veterinary Pharmacopoeia and China Veterinary Medicine Protocols, when they choose appropriate treatment for cows infected with mastitis, isolate the sick cows with others, and sterilize and use separate milking tools on them. The milk from cows that have been treated with antibiotics within the last 72-92hours will be disposed and prevented from going into the market.

Q: What are the main effects of long-term antibiotic consumption?

A: The first thing is that they can kill the friendly bacteria in our digestive system, and instead left those antibiotic-resistant bacteria alive. Therefore it increases their tolerance to drugs, and poses problems with clinically treating the patient with antibiotics in the future. Also for some people it may cause anaphylactic reactions. Not to mention that some of the antibiotics are neurotoxic or harmful to particular parts of the body, like tetracycline, which weakens the teeth.

Dr. Meng thinks our method, if commercialized, will mostly benefit people in the rural area, where most milk they consume doesn't go through the large dairy processing company, but straight from the farmer to customers. This type of milk is indeed fresher than those purchased from the market, but it doesn't go through the whole series of quality test, either. And it's unrealistic to run the test on the diary farm without convenient and accessible methods. 

And we took a tour in the plant of Sanyuan Milk Group, one of China’s largest dairy processing companies, and witnessed the strict process of sampling and testing the milk transported from individual farms, passing the HPLC test, before taking the milk in for further process.

The milk that comes out of companies like San Yuan has a higher quality, but also a higher price. But in the relatively poor areas where the main source of milk are not processed according to this kind of procedures, people has a greater chance at consuming disqualified milk.

Integrated Practice

With the information gathered from research and outreach, we understand that our approach would bring out the best outcome if we make it as cheap and accessible as possible. So we want to seek ways to slightly modify the way to measure the enzymic activity, and make it more cost-effective.

Since testing fluorescence intensity only requires wave lengths from 450nm to 490nm, we redesigned the spectrophotometer, using Charge Coupled Device, so that it emit monochromatic light that only excites green fluorescence, and the cost of manufacturing would be much cheaper compared to the usual ultraviolet-visible spectrophotometers used in labs. (See more in project optimization).

This combined with our 1.0 approach with PBP5-GFP (see more in project 1.0), can be specifically used to detect penicillin residues. And Dr. Dao He, a physics teacher in our school with a PhD in nuclear physics at Tsing Hua University, thinks our new design is viable if some tech company help manufacture the light-emitting component. Unfortunately we do not have enough time to find such a manufacturer, but as we work toward the commercialization of our project, we have confidence our new penicillin detection method has the potential of being applied to poor areas of the country, probably in every “Milk Bar” or small-scale farm, because purchasing a test machine will no longer be impossible, so that everyone in China has a better chance at drinking qualified milk.