The Effects of Hydrochloric Acid and UV Radiation on E. Coli

1. The Effects of Hydrochloric Acid and UV Radiation on E. Coli David Foody Central Catholic High School Grade 9

2. Escherichia coli (E. coli) • Large and diverse group of gram (-) bacteria • Free living, symbionts, or pathogens • Most strains are not pathogenic • Serve as a common prokaryotic cell model • Common mammalian intestinal symbiont • Environmental prokaryotic model

3. Electromagnetic Spectrum • Diagram showing the range of all types of frequencies of electromagnetic radiation • The types of radiation are radio waves, microwaves, infrared, visible, ultraviolet, x-rays, and gamma rays

4. Ultraviolet Radiation • Ultraviolet (UV) rays are light rays that have shorter wavelengths than visible light • Range from 150nm – 300nm • They are naturally given off by the sun, but most are absorbed by the ozone layer • The wavelength used in this experiment is 254nm light

5. pH pH Scale Neutralization The mixture of an acid and a base. Mixture of acid and base commonly yields water • Measures how acidic or basic a substance is • Scale from 0-14 • pH < 7 acidic, pH > 7 basic, pH = 7 neutral

6. Hydrochloric Acid • Forms an organic salt when it reacts with an organic base • Strong mineral acid • pH level of 3 • Highly corrosive • Often used to restore metals

7. Purpose • Test the survivorship of E. Coli when exposed to Ultraviolet Radiation and Hydrochloric Acid. • Determine if radiation from the sun affects the refinements of ores

8. Question • Will differing amounts of Hydrochloric Acid and ultraviolet radiation have a significant effect on E. Coli?

9. Hypothesis • Null Hypothesis: The Hydrochloric Acid and ultraviolet Radiation will not have a significant effect on the resulting amount of E. Coli. • Alternative Hypothesis: As the concentration of Hydrochloric Acid and exposure to ultraviolet radiation increases, the survivorship of the E. Coli will decrease.

10. Materials • LB Agar Plates • Spreader Bars • Ethanol • Matches • Hydrochloric Acid (HCl) • Water • Escherichia Coli • UV Lamp (254 nm) • Incubator • Test Tubes • Stopwatch • Vortex Machine • PH Strips • Sterile Dilution Fluid

11. Procedure • Bacteria (E. Coli) was grown overnight in LB Media • A Sample of the Overnight Culture was added to fresh media in a Sterile Sidearm Flask • The Culture was placed in an incubator until a density of 50 Klett spectrophotometer units was reached. This represents a cell density of approximately 108 cells/mL. • The culture was diluted in sterile dilution fluid to a concentration of approximately 108 cells/mL. • Various concentrations of Hydrochloric Acid were created in test tubes containing SDF, resulting in 9.9 mL per tube

12. Concentrations

13. Procedure (Continued) • 0.1 ml of E. Coli was then added to the test tubes, yielding a final volume of 10 mL. • The solutions were mixed by vortexing and allowed to sit at room temperature for 10 minutes. • After vortexing to evenly suspend cells, 0.1 ml was removed from the tubes and spread on LB plates. • Plates were then placed under a UV lamp for specific times (3 seconds and 6 seconds) • The plates were incubated at 37°C for 24 hours • The resulting colonies were counted. Each colony is assumed to have arisen from one cell.

14. E. Coli Colonies with No Radiation Results

15. Individual Stat Analysis

16. E. Coli with 3 Second Radiation Results

17. Individual Stat Analysis

18. E. Coli with 6 Second Radiation Results

19. Individual Stat Analysis

20. Conclusion • Null hypothesis: The Hydrochloric Acid and ultraviolet Radiation will not have a significant effect on the resulting amount of E. Coli. • Null Rejected • All colonies exposed to Ultraviolet Radiation and Hydrochloric Acid had a significant effect. • The longer the E. Coli was exposed to UV Radiation and the lower the pH level of Acid, the lower the E. Coli survivorship

21. Future Experimentation and Limitations Future Experimentation Limitation Some sunlight was shining into the room while spreading the plates Only 1 species tested Only survivorship was tested • More pH levels and times for UV Radiation could be used • Use different chemicals • Use other sources of radiation

22. Sources • Website Title: Centers for Disease Control and Prevention Article Title: E.coli (Escherichia coli) Publisher: Centers for Disease Control and Prevention Electronically Published: January 25, 2018 https://www.cdc.gov/ecoli/index.html • Website Title:HealthlineArticle Title: E. Coli Infection: Causes, Symptoms, and Prevention Publisher:Healthline Media https://www.healthline.com/health/e-coli-infection • Website Title: National Center for Biotechnology Information. PubChem Compound Database Article Title: hydrochloric acid Publisher: U.S. National Library of Medicinehttps://pubchem.ncbi.nlm.nih.gov/compound/hydrochloric_acid • Website Title: HYDROCHLORIC ACID, SOLUTION | CAMEO Chemicals | NOAA Article Title: Search Chemicals Author: NOAA Office of Response and Restoration, US GOV https://cameochemicals.noaa.gov/chemical/3598 • Website Title: American Cancer Society Article Title: What Is Ultraviolet (UV) Radiation? https://www.cancer.org/cancer/skin-cancer/prevention-and-early-detection/what-is-uv-radiation.html • Website Title: LiveScience Article Title: What Is Ultraviolet Light? Publisher:PurchElectronically Published: September 15, 2017 Author: Jim Lucas https://www.livescience.com/50326-what-is-ultraviolet-light.html