The Effects of Chlorinated Water on Microbial Life

1. The Effects of Chlorinated Water on Microbial Life Jeff Van Kooten 9th Grade Central Catholic High School

2. Chlorine’s Use in Sanitation • The most common substance used in water sanitation • Solid, liquid, and gaseous form • An important reaction occurs that allows sanitization • When chlorine (Cl2) is added to water (H20), a chemical reaction occurs that produces hypochlorous acid (HOCl) and hypochloric acid (HCI) • CI2+H20 HOCI+ HCI • Hypochlorous acid is the active, killing form of chlorine • When Hypochlorous encounters a nitrogen or ammonia, it becomes a chloramine (which is not capable of sanitation)

3. Chlorinated Water Primary factors affecting the disinfection of water using chlorine include: 1. Type of chlorine 2. pH of pool water 3. Water concentration of dissolved contaminants in the pool 4. Water temperature 5. Duration of exposure

4. pH level is between 7.8 - 8.2 Higher pH reduces the sanitizing power of the chlorine due to reduced oxidation-reduction potential (ORP), Lower pH causes discomfort to swimmers Kept around 40 ppm Once a week the pool undergoes a shock treatment, uses chlorine in the form of sodium hypochlorite (bleach) Chartiers Valley Pool Water

5. Yeast Single-celled fungi Eukaryotes even though they have some traits of prokaryotes Most commonly studied organism- similar biochemistry and genes as other Eukaryotes

6. E. coli Common symbiont found in the colon of animals (human) Gram negative bacteria Most commonly studied Prokaryote Most strains non pathogenic Easy to culture and work with

7. Purpose To examine the effects of chlorinated water on Yeast and E. coli survivorship

8. Hypothesis Null Hypothesis: Chlorinated pool water will not have a significant effect on Yeast and E. coli survivorship. Alternative Hypothesis: Chlorinated pool water will significantly reduce Yeast and E. coli survivorship.

9. Materials YEPD agar plates (YEPD media + 1.5% agar) YEPD media (1% yeast extract, 2% peptone, 2% glucose) LB agar plates LB media (0.5% yeast extract, 1% tryptone, 1% sodium chloride) Sterile Dilution Fluid [SDF] (100mM KH2PO4, 100mM K2HPO4, 10mM MgSO4, 1mM NaCI) Sterile pipette tips Micropipettes Vortex Incubator • Sidearm flask • Spreading turntable • Spreader bar • Ethyl alcohol • Sterile capped test tubes with Sterile distilled water. • Saccharomyces cerevisiae (Yeast) • DH5-Alpha (E. coli) • 0.22 micron syringe filters + 10mL syringe • Klett Spectrophotometer • Chlorinated pool water

10. Procedure 1) Pool water was obtained from Chartiers Valley Swim Pool and sterile filtered with 0.22 micron syringe filters 2) Yeast and E. coli were grown overnight in sterile YEPD and LB media 3) The cultures were placed in an incubator until a density of 50 Klett spectrophotometer was reached. This is a density of about 107 cells/mL 4) The cultures were then diluted in Sterile Dilution Fluid to a concentration of 105 cells/mL 5) The chlorinated water was diluted with sterile dilution fluid to concentrations of 0%, 10%, 50%, and 99% (to total 9.9 ml) 0.1 ml. of cell culture was then added to the test tubes, yielding a final volume of 10 ml, and a cell density of approximately 103 cells/ml. 7 5

11. Procedure (Continued)

12. Procedure Continued 6) The tubes were allowed to incubate at room temperature for 20 minutes. 7) After vortexing to evenly suspend cells, 0.1 ml. aliquots were removed from the tubes and spread either YEDP or LB agar plates. 7) The E. coli was incubated for 24 hours at 37C and the yeast was incubated for 48 hours at 30C 8) The resulting colonies were counted. Each colony is assumed to have arisen from one cell.

13. Pool waters effect on Yeast P-value: .098755 130.33 113.66 109.16 [colonies] 89.33 [Pool water]

14. Pool waters effect on E. coli P-value: 5.66x10-6 299.83 214 [Colonies] 161.5 101 [Pool water]

15. Dunnett’s Test Table T crit.=3.10 Alpha=.05 E. Coli T value Interpretation 10% .789 not significant 50% 2.934 not significant 99% 4.74 Significant

16. Yeast Analysis The Anova test did not reveal significant variation among the means, thus Dunnett’s test could not be performed The null hypothesis has to be accepted, there was no evidence that the pool water reduced yeast survivorship

17. E. coli Analysis • Anova revealed significant variation between the means • The Dunnett’stest revealed significant variation withthe 99% group • The null hypothesis rejected only for the 99% group

18. Limitations and Extensions Limitations Synergizing the spreading of plates more precisely Water might have had chloramines in it, making the water less effective Extensions Increase trial size to 20 or 30 for more accurate results exposure time to the water Conduct test on different micro organisms Determine the solute concentrations in water, providing evidence for or against osmotic shock

19. References www.poolcenter.com/chlor.htm www.pested.msu.edu/Resources/Bulletins/pdf/2621/e2621chap7.pdf http://water.epa.gov/drink/contaminats/basienformation/ecoli.cfm#four http://ict-science-to-society.org/pathogenomics/EcoliandSalmonella.htm http://answer.yahoo.com/question/index?quid=20070606205537AAygisg

20. Yeast Anova

21. E. Coli Anova