Colorado is the point of origin of many important waterways in the United States. It provides water for large parts of the midwest, and is vital to water security in the arid states to the south and west. Unfortunately, many regions of Colorado suffer from groundwater contamination due to fracking and other fossil fuel extraction processes. Given the rapid rate of climate change it is vital to protect our sources of water. For this reason, we are developing a biosensor to detect naphthalene, a common element in industrial processing and fracking. Our biosensor will detect low levels of naphthalene in the environment and respond by expressing RFP in a self amplifying manner. The result is that the culture will completely turn red even if only a single cell detected naphthalene, the inducer. The biosensor will be housed in a small photovoltaic powered device for onsite contamination identification. Currently we do not have any detection that is ever vigilant, the sensor we are developing will enable environmental groups and petroleum companies to protect the world's water supplies without the high cost of environmental disaster cleanup.
To build the biosensor we had to explore two inducible promoter systems. The first promoter, psaI, will respond to naphthalene. We have placed this promoter upstream of the integrase Bxb1. When Bxb1 is expressed, the integrase will flip a logic gate, designated by attB and attP sites, that contains a terminator sequence. Once the logic gate is flipped, the terminator will be inactivated leading to expression of LuxI, which creates AHL by interacting with SAM. AHL is a small molecule used by V. fischeri for cell to cell signaling. AHL will act on a second inducible promoter, the luxCDABE, which is placed upstream of LuxI and RFP. The expression of any AHL will cause signal amplification throughout the entire population. The result is a visible phenotypic change in the entire cell culture based on the induction of as few as 1 or 2 cells.
The biosensor will be housed in a small, stake-like device using photovoltaic cells to maintain environmental conditions and gather water samples from the environment for analysis. A central chamber with a viewing window will contain the biosensor at slow growth conditions. A pump system will obtain water from the environment and deliver it to the biosensor culture. Once a target molecule, naphthalene, has been encountered the culture will express RFP leading to a visual change. This sensor will be able to sit in the field for days or weeks at a time, constantly sampling the environment for contamination. This ever-vigilant sensor will greatly increase our water security without slowing our energy extraction.