Our team’s goal is to engineer a novel solution in preventing and addressing eutrophication in lakes, streams, and rivers not only in South Korea, but around the world. As with any other social environmental issue, we believe that an effective solution to eutrophication begins by first identifying and visualizing its adverse effects. Our team imagines a ‘surveillance system’ of sorts that is capable of taking many nitrate samples over a given body of water, realized through the use of cost-effective and robust nitrate biosensors.
Our team aims to develop a novel nitrate sensor using synthetic biology, which can identify the nitrate concentration underwater and express it on an easy chromatic scale — green, yellow, and red — depending on the degree of concentration. Therefore, we used modified E. coli and created beads that change color according to nitrate concentration. Under normal conditions, the beads maintain a green color. However, as the nitrate concentration increases, the beads gradually change from green to yellow to red. Furthermore, we adopted an Arduino color sensor to convert this color information into easily measurable electric signals.
The mVenus level is dominant before nitrate is added, causing the beads to show a green color. However, the addition of nitrate causes the beads to slowly turn red over time. Since quantitative measurement of the fluorescence using UV radiation causes viability decrease, we qualitatively observed how the color changes over time post-nitrate addition. In a 10mM nitrate solution, the color of the beads changed from green to notably red after 6 hours.
Also, we could observe that the expression level of mScarlet varied according to the concentration of various nitrate solutions, which also caused the beads’ colors to alter accordingly. While the color change was noticeable to our naked eyes, it became more obvious when treated with UV lights.
Monitro measures the nitrate concentration in a unit of µM within four to six hours by using an RGB color sensor connected to the Arduino circuit board with E.coli indicators encapsulated in alginate beads. Users can easily insert alginate beads into the sensor and obtain data on their mobile devices. Through Wi-Fi transmission, the Arduino chips can deliver data wirelessly to our software and provide accurate information about nitrate concentration.
We also created an application that shows the nitrate concentration with the RGB value retrieved from the sensors. This could be used to predict the possibility of eutrophication. In this way, this technology can be extrapolated beyond detecting nitrates, but also different ions in the water, which could potentially benefit the environment.
