Team:Nanjing-China/Description

What inspired our team?

Before making the ultimate decision, we tried several topics like modifying a target, improving the accuracy of a medicine. However, the condition of waste water finally seized our attention. One of our team members, whose hometown is near the Lake Tai, mentioned that Lake Tai was heavily polluted by chemical fertilizer and pesticides. So we decided to figure out a way to solve that. We soon found that nitrogen and phosphorus pollution are the two major pollution, and phosphorus pollution is the hardest one to deal with. As is often the case, low concentration of phosphorus in waste water and high reclamation cost cause the low removal efficiency of phosphorus. After conducting the survey about how to reuse wasted phosphorus, we found that the problem could not be solved only by chemistry, since single chemical method needs high concentration and valuable metal ions. To collect the scattered phosphorus and create a way to produce raw materials for fertilizer, we decide to employ cell engineering bacteria. This topic is a bridge between agriculture and industry, which eases the conflict of them and is good to fertilizer production. It succeed to attract our interest.

What are we doing?

Our team is trying to figure out an innovative way to process the sewage and therefore generate energy for the growth of crops. Our bacteria will be engineered to make the Phosphorus in the sewage concentrated rapidly. In the inorganic experiments, we will find the suitable concentration of phosphate radical for the formation of struvite. Our bacteria can process the sewage and make it a new source of energy which can be used in the plantation of most crops.

We have known that the phosphorus cycle is complicated progress (the cycle is shown below), and phosphorus plays and important role during the growth of plants and in the development of industry. The production of fertilizer cost large amount of phosphorus and the natural mineral which take many years to accumulate is limited. So we cast our focus on the reclamation of phosphorus in waste water.

The raw material of phosphorus minerals are exploited and then consumed in industry. Then the waste phosphorus are discharged in low concentration(about 50mg/L) to water. The concentration is too low to collect phosphorus with chemical method, so the first step we need to do is to converge the polluted water and put our cell engineering bacteria into the water.

After adding the special-made bacteria, the simple substance phosphorus will be collected by the bacteria. Our bacteria are able to take in phosphorus without caring about the concentration situation and then synthesize them into polyphosphates. The bacteria are sensitive to magnesium ion concentration. The moment when the satiated bacteria are put to the pool rich in magnesium ion, they will soon give out the phosphorus. Next, we are going to create the main material of our fertilizer, NH4MgPO4·6H2O.

Before talking about the synthesis of NH4MgPO4·6H2O, we need to greet the bacteria. As prokaryotes, they are able to synthesize polyphosphates with the help of polyphosphokinase.

The feasibility of our project

The methods and technology we will use in the experiments, such as plasmid construction, transformation and so on, are all traditional tools in synthetic biology. We have abundant knowledge about them and there are number of data and document we can refer to. Meanwhile, we can simulate the condition of sewage in the nature to test the P-concentration ability of our constructed bacteria. Our laboratory is equipped with suitable environment where many useful crops can grow as they are in the natural field. Therefore, we can test how much energy we can provide via our transformation of the bacteria.