The Effects Of Drain Cleaner on Microbes Matt Zagrocki Central Catholic High School Grade 9

Problem What effect does drain cleaner have on the survivorship of Escherichia coli?

Purpose This experiment was conducted to see the effect drain cleaner has on E. coli. Will it decrease survivorship? Does concentration have an effect? Are eco friendly drain cleaners less damaging?

Application to the Real World Drain cleaners are commonly used by the American household Substances poured down drains can leak into the watershed E. coli was used to model fresh water prokaryotes Can a drain cleaner effectively sterilize household sinks and drains?

Drano Max Gel (industrial) Widely used Main ingredient is Sodium Hydroxide, a caustic Other ingredients include sodium hypochlorite, (bleach) water, sodium silicate (corrosion inhibitor) and a surfactant blend (cleaning agent) pH of 11

Sodium Hydroxide Molecular formula NaOH Highly reactive with other metals Corrosive to living matter Also referred to as lye Synthetically manufactured

Green Gobbler (eco friendly) Claimed to be biodegradable and eco-friendly EPA approved Unnamed hydroxide identified as “trade secret/proprietary” Ph of 13 Other ingredients are water, xanthan gum, alcohol ethoxylate, modified magnesium silicate

Escherichia coli Common bacteria found in intestinal tract of animals Works its way into water through feces Gram Negative Ubiquitous classified as a facultative anaerobe Thrives in pH neutral environment Survives in pH range 4.4-9.7

Hypothesis Null Hypothesis – The drain cleaners will have no effect on E. Coli Alternate Hypothesis – The drain cleaners will significantly reduce survivorship of E. coli Green Gobbler will have less negative effects on E. coli survivorship than Drano

Materials LB Agar Plates (0.5% yeast extract, 1% tryptone, 1% sodium chloride) Pipettes (p. 20, 200, and 1000) %70 Ethanol (to sterilize) E. coli Permanent Marker Drano Max Gel Drain Cleaner Vortex Green Gobbler Eco-Friendly Drain Cleaner Test Tubes (sterile) Test tube racks Sterile Dilution Fluid (10mm KH2PO4, 1 mm MgSO4, .1mm CaCl2, 100 mm NaCl) Spreader Bars

Procedures 1. E. coli was grown overnight in sterile LB media. 2. Samples of the overnight cultures were added to fresh media in sterile sidearm flasks. 3. The cultures were placed in an incubator (37°C) until a density of 50 Klett spectrophotometer units was reached. This represents a cell density of approximately 108 cells/mL. 4. The cultures were diluted in sterile dilution fluid to a concentration of approximately 105 cells/mL.

Procedures (continued) 5. Six test tubes were set up as follows: 10% 1% 0.1% 0.01% 0.001% 0% E. Coli 1 mL of drain cleaner 0.1 0.01 Substock mL of sterile dilution fluid 8 8.9 8.99 9 Total volume 10

Procedures (continued) 6. The tubes were vortexed and allowed to sit in room temperature for 10 minutes 7. 0.1 mL aliquots were pipetted onto agar plates 8. The plates were placed in an incubator for 24 hours, and then the colonies were counted visually. Each colony was assumed to have arisen from one cell.

E. Coli Survivorship in different concentrations of Drano P = 3.5E-26

Dunnett’s Test- Drano T crit – 3.39 P value < 0.05 Concentration T Value Result 0.001% 22.23045 Significant 0.01% 31.1894 0.1% 34.86225307 1% 10% T crit – 3.39

E. Coli Survivorship in different concentrations of Green Gobbler P = 4.7E-27

Dunnett’s Test – Green Gobbler P value < 0.05 Concentration T Value Result 0.001% 8.4569076336 Significant 0.01% 22.2434517741 0.1% 32.459446345 1% 34.86225307 10% T crit – 3.39

P = 3.5E-26 P = 4.7E-27 P < 0.05 P < 0.05 P < 0.05

Conclusions Null Hypothesis was rejected All concentrations with both drain cleaners had a significant effect Drano appeared to have a greater negative impact at lower concentrations Higher concentrations killed more colonies

Limitations Only one bacteria was used Only 5 concentrations were tested Only two types of drain cleaner were tested Plating, vortexing, pipetting, and exposure times could have been slightly unsynchronized Study does not reveal other effects on bacterial health

Extensions Use different types of bacteria Use more types of drain cleaner Use different exposure times Additional trials per group

Sources “DISSOLVE Drain Opener - Liquid Hair&Grease Clog Remover (32 oz.).” Green Gobbler, greengobbler.com/products/dissolve-liquid-hair-grease-clog- remover?variant=12039958657. “Max Gel Clog Remover.” Drano® | SC Johnson, www.drano.com/en- us/products/drano-max-gel-clog-remover. “SODIUM HYDROXIDE.” National Center for Biotechnology Information. PubChem Compound Database, U.S. National Library of Medicine, pubchem.ncbi.nlm.nih.gov/compound/sodium_hydroxide. “E.coli (Escherichia coli).” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 25 Jan. 2018, www.cdc.gov/ecoli/index.html.

Anovas Anova- Single Factor / Drano SUMMARY Groups Count Sum Average Variance x 6 .1x .01x .001x 274 45.6666667 135.466667 .0001x 941 156.833333 1920.56667 0x (control) 2597 432.833333 718.566667 ANOVA Source of Variation SS df MS F P-value F crit Between Groups 880512.556 5 176102.511 380.817079 3.4886E-26 2.53355455 Within Groups 13873 30 462.433333 Total 894385.556 35   Anova: Single Factor / Green Gobbler SUMMARY Groups Count Sum Average Variance x 6 .1x .01x 179 29.8333333 190.166667 .001x 940 156.666667 773.866667 .0001x 1967 327.833333 1137.36667 0x (control) 2597 432.833333 718.566667 ANOVA Source of Variation SS df MS F P-value F crit Between Groups 1024398.47 5 204879.694 435.919396 4.7456E-27 2.53355455 Within Groups 14099.8333 30 469.994444 Total 1038498.31 35