Team:GenetiX Tec CCM/Design
So what is denitrification?
The denitrification process starts with several metalloproteinase catalyzing the transformation of nitrites to nitrates; these nitrates are then transformed to nitric oxide; which in turn are converted into nitrous oxide; and finally into molecular nitrogen.
Within the nitrogen cycle, there are two processes complementary to each other: nitrification and denitrification. Both are conducted by different kinds of bacteria. The first one, nitrification, is an aerobic process, which transforms ammonia (NH4) to nitrates (NO3). On the other hand, denitrification, is an anaerobic process, which “continues” the process of nitrification, and which can be summarized with the following reactions’ schematic:
Due to the nature of nitrates and nitrites as potential eutrophication factors, the nitrification-denitrification process is often exploited by governments to reduce the amount of NO3 and NO2 present in water where wastewater is disposed, transforming them into N2. As denitrification is a process entirely carried out by bacteria. We see an opportunity to create a biological system which is capable of carrying out this process for the same purpose, but only within regulated conditions or parameters that we are capable of controlling and establishing beforehand.
In the figure 1 the denitrification process is explained. Denitrification encases many reductions of nitrogen and oxygen bonds, for example the NO2, NO3 and NO. This is a multistage process and so the diagram explains it broadly. The first cluster to take action in the chain is the Nar cluster, in here the NarH, NarG and NarL reductases take Nitrate (NO3) and transform it into NO2, leaving Oxygen behind. After this the next stage is taken by the Nir cluster. In this cluster the NirQ protein starts to encode for Nitrites in the environment, and so the Nitrites are further reduced to Nitric Oxide (NO).
The next process starts when the bacteria bonds the nitrogen dissolved into the Nitric Oxide by the means of the Nor Cluster to form Nitrous Oxide (N2O) , effectively lowering levels of Nitrogen in the water. The last part of the process involves reducing further the newly formed Nitrous Oxide into its basic components, Molecular Nitrogen and Oxygen. This final part of the process is achieved by the Nos cluster; after it is decomposed into both the Nitrogen and Oxygen the Nitrogen is released as gaseous element and the Oxygen is dissolved in the water. As a result the oxygen levels rise, reducing the anoxia.
Previous Work
Last year our team participated in the high school division with a project that started the development of a biosensor using an oxygen (BBa_K258005) and iron (BBa_I765000) promoter, this activates a reporter. We took the GFP (BBa_E1010) and mRFP (BBa_J04650) as indicators. The system was created in order to develop a precise and economical way to measure low levels of oxygen dissolved in water. Iron promoter was used to exemplify as a method to quantify heavy metals as Hg or Pb. Creating the biosensor helps to report the actual conditions of the water in Xochimilco. Ultimately this information would reach the citizens, council and governmental institutions. For further information about our last project click here
What is the problem in Xochimilco?
Xochimilco is an important zone in México City´s economy. Around 396,852 people live here. People are in improper conditions of settlement. Approximately 14% of the houses are a single room or with ground floor. The zone also has a lack of a drainage system which gives an average amount of more than 30,000 faeces downloads per day are discharged directly into the canals. This brings an enormous increase of the pollution of water. The added nutrients on contaminated water causes water lily to atrophy the channels. Lily roots and attacks the endemic trees of the place: the ahuejote, used to create and settle chinampas. Covered lily channels prevent the path to the chinampas, which are abandoned as agricultural production premises; they urbanize and create more wastewater discharges. Those factors contribute to a reduction in the production of crops and animals of the small