1. The role of cell characteristic on sunlight-mediated photochemical disinfection in agricultural run-off waters James Gutierrez- BRITE Student Amy Gong-BRITE Mentor Dr. Sharon Walker- BRITE Faculty Advisor UCR Bacterial Adhesion Research Laboratory

2. Relevance http://www.pcee.org/Images/Images_Questions/06_12_11_point_non_point.gif

3. Cellular Characteristic Zeta Potential Hydrophobicity Cell Lysis test EPS analysis Size Viability Surface charge

4. What are Extracellular Polymeric Substances? Copyright © 2008 American Chemical Society Amount and composition vary due to physiology, growth phase, pH, temperature and other environmental factors Made up (usually) primarily of polysaccharides (sugars) and proteins with traces amounts of nucleic acids

5. EPS extraction methods Azeredo and Lazarova Cold ethanol Sonication +

6. Simplified system No addition “quenchers” are needed No catalyst needed Common pollutant from agricultural run off Photo-chemical Transformation NO 3 -. NO 3 - + NO 3 - NO 2 - + O (3P) NO 2 - +. O - Followed by. O - + H 2 O. OH + OH - light Why Nitrate? Halmann, M. M. (1996). Photodegradation of water pollutants. Boca Raton: CRC Press.

7. How Hydroxyl Radical kills Disrupts the cell membrane

8. D21G Photolysis

9. HU1 Photolysis

10. DC1 Photolysis

11. Hydrophobicity Microbial Adhesion to Hydrocarbon (MATH) test

12. Zeta Potential

13. EPS Cell TypeMean Sugar a Content (mg/cell x 10 11 ) Mean Protein b Content (mg/cell x 10 11 ) Average Sugar to Protein Ratio Average Cell Concentration (10 11 bac/mL) D21g 2.6258.78 0.05 0.30 HU1 2.0876.16 0.04 0.42 DC1 1.4161.21 0.04 0.61 a Based on Xanthan gum as the standard. b Based on Bovine Serum Albumin (BSA) as the standard.

14. Discussion Increased concentration of nitrate increases bacterial kill rates. Further work will include Dissolved Organic Matter. Yet to identify the role of EPS. We suspect that EPS is assisting the bactericidal effect.

15. Future work Finish tests in triplicate Begin testing in Sun simulator with low, medium and high EPS E. coli strains Quantify the reaction rate and rate constants for bactericide Identify solution chemistry effect of the photochemical disinfection Optimized condition for the reaction to take place

16. Acknowledgments The BRITE program and BRITE participants. UCR Bacterial Adhesion Research Lab members Dr. Sharon Walker Amy Gong