As of 2019, modern agriculture could only sustain about 7 billion of the projected 8 billion+ people in the world, and as a result, global cereal crop production has doubled over the past 40 years [1]. The main method for combatting this issue is increasing the use of nitrate fertilizer. Nitrate is the most limiting factor for plant growth and is an essential nutrient for them. Though these fertilizers have had the desired effect of increasing global crop yields, they have exacerbated the issue of nitrate runoff.
Lake Decatur is a reservoir found in Illinois. Lake Decatur supplies 39.4 million gallons of water a day to 87,000 people in Decatur and surrounding communities. However, the water supplied from Lake Decatur has been deemed unsafe to drink due to high concentrations of nitrate. The high levels in Decatur result from nitrate leaching, the loss of nitrogen in agricultural systems. In recent years, there has been an increased demand for nitrate containing fertilizers. Though this has helped boost crop production, the excess nitrate in the soil has created negative environmental impacts. Nitrate has found ways to get into waterways due to the nitrate in the fertilizer, creating unsafe drinking water conditions and disruptions in the aquatic ecosystem by over-stimulating plant growth.
Our idea was inspired by studies from Tay et al., who created engineered catalytic biofilms to capture heavy metals [2], [3]. Our approach will utilize the Biofilm Integrated Nanofiber Display (BIND) strategy developed by Botyanszki et al. in which the SpyTag/SpyCatcher attachment system is used to site-specifically immobilize a protein onto bacterial nanofibers [4]. The activity of the immobilized protein is independent of the cell - it can remain active even after cell death or if the fibers are unattached from the cell [2], [4]. We aim to first test the ability of our construct to capture nitrate by creating a cell-free engineered nanofiber mesh. Then, we hope to modify our system into a cellular system that can be induced in the presence of nitrate.
References
[1] Z.-H. Wang and S.-X. Li, “Chapter Three - Nitrate N loss by leaching and surface runoff in agricultural land: A global issue (a review),” in Advances in Agronomy, vol. 156, D. L. Sparks, Ed. Academic Press, 2019, pp. 159–217. doi: 10.1016/bs.agron.2019.01.007.
[2] P. K. R. Tay, A. Manjula-Basavanna, and N. S. Joshi, “Repurposing bacterial extracellular matrix for selective and differential abstraction of rare earth elements,” Green Chem., vol. 20, no. 15, pp. 3512–3520, Jul. 2018, doi: 10.1039/C8GC01355A.
[3] P. K. R. Tay, P. Q. Nguyen, and N. S. Joshi, “A Synthetic Circuit for Mercury Bioremediation Using Self-Assembling Functional Amyloids,” ACS Synth. Biol., vol. 6, no. 10, pp. 1841–1850, Oct. 2017, doi: 10.1021/acssynbio.7b00137.
[4] Z. Botyanszki, P. K. R. Tay, P. Q. Nguyen, M. G. Nussbaumer, and N. S. Joshi, “Engineered catalytic biofilms: Site-specific enzyme immobilization onto E. coli curli nanofibers,” Biotechnology and Bioengineering, vol. 112, no. 10, pp. 2016–2024, 2015, doi: 10.1002/bit.25638.
Thanks for the collaborator teams and the sponsor of our university
