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Clean drinking water for everyone

The Decision: The process to decide what you want to make for the iGEM competition is not an easy one. Because of the almost limitless possibilities that this technology offers, we started out with almost three pages of ideas. Over the course of weeks we were able to narrow it down to two and we have finally decided what we will build. We will build floating bacteria that are able to purify water of heavy metals.

The pollution of our rivers and lakes with heavy metals is a serious problem, and with the booming economies in the Far East it will become an even greater problem in future. Not only will it effect our environment, it also endangers the amount of drinking water that we have. This will not only be a problem in developing countries but also here in The West. Up till now there is no cheap and effective method to handle this problem. In many cases after the source of the pollution is stopped, one hopes that nature can handle the disposal of already dumped heavy metals herself. In very extreme cases the entire sediment of the riverbed is removed to be taken to a CDF (Confined Disposal Facility), which is nothing more than a garbage dump for the sediment.

Our Goals: We hope that our bacteria will provide a cheap and efficient method of cleaning this sediment. Our first goal is to create a bacterium that is able to absorb and encapsulate metals and that floats. In this way one would be able to separate the metals and the sediment. Simply put the bacteria and the sediment in large container stir them together and let the cleaned sediment sink and scoop of the floating metal filled bacteria. Such a purification plant would look similar like the sewage disposal plants that we use today.

Out second goal is to create a bacterium which does not float, starts accumulating metals and when it is ‘full’ floats to the surface. This would allow on site purification. Simply inject the bacteria in the sediment, let the bacteria that are full of metals float to the surface and collect them further downstream with the help floaters which are now used to contain oil pollution in the sea.

Our last idea needs a bit of an introduction. Over thirty years ago foreign aid organizations under the leadership of UNICEF and the WHO, with the financial support of the World Bank decided to battle against cholera and other bacteriological deceases in Bangladesh and other countries. In less than two decades over ten million water pumps where installed with spectacular results. An unforeseen consequence was that because the groundwater level dropped dramatically, arsenic which had been delivered by the Ganges and the Brahmaputra for over thousands of years began oxidizing. This created a poisonous solution which is hard to notice because it has a neither smell nor taste and whose effects are only noticed after decades. At this moment tens of millions of people are at the risk of arsenic poising. We hope that it will be possible to create an organism as robust and cheap as yeast, used for making bread, with the capabilities of the organism we are trying to create. People would be able to let the organisms grow in their water tank and scoop of the floating layer. When the bacteria no longer start to float the water is cleansed. It should only be cooked to kill of the remaining organisms. We do not aim to create such an organism; however we hope to present you with a proof of principle.

What we will do: For iGEM we hope to realize our first and second goal. This means we create an organism that can detect metal, transport it inside the cell, store it inside the cell in such a way that it does not harm the cell and finally when the cell is full creates gas vesicles that makes it float on the surface of the water. Furthermore it should not be an environmental hazard by itself, but on the other hand it should be able to maintain itself for a period of time in order to be able to clean the water. In the course of the next three months we only address this problem in theory. Thus our organism will perform its task without any other organisms near it. It will be tested in a colomn with some sediment and with a predetermined quantity of metals. Furthermore we will not try to clean the water of all metals and the water will only contain that metal which the bacteria are supposed to get rid of. At this moment we are looking at Copper, Zinc, Arsenite, heavy metal uptake coupled to citrate and Periplasmic accumulation of heavy metals via Mer Operon. In general there is lots information available on all points and almost all points; uptake, transport, storage and floatation have been done by itself or at least the genetic code is available. For details on the matter I would like to direct the reader to our “The Project” section. How everything works together has not been tested.

Herein lies most of our potential problems. Starting with the uptake of metals, the system used to take metals into the cell is sometimes the same as the system taking metals out of the cell, so that the cell in total does not accumulate metals. When we manage to block the outflow of metals, if the metals are not encapsulated or neutralized they could poison the bacterium. Even when the bacterium is able to safely accumulate metals, the promoter that activates gas vesicle production might fail to operate and finally if everything works just fine gas vesicle production might not function optimally and the organism still fail to float.

Not everything is that grim however. We are quite confident that we will be able to create a bacterium that is able to accumulate metals; also we should be able to recreate the results of Melbourne from 2007. A little bit trickier will be to combine the two organisms into one, furthermore in order to reach our second goal the buoyancy should be better than that what Melbourne was able to do in 2007, because we want a thin film at the top of the water and not a suspension. The trickiest part will be to activate the gas vesicle production gene at the moment the cell is filled with metals.

To fulfill our first goal of removing heavy metals from sediment in a CDF we only need bacteria that are able to accumulate metals and have the same buoyancy capabilities that Melbourne was able to create in 2007. We are almost completely confident that we are able to achieve it and we are looking forward to presenting our project at the Jamboree.

iGEM Team Groningen 2009