View
217
Download
0
Category
Tags:
Preview:
Citation preview
EFFECTS OF FRACKING FLUID ON STAPH. EPIDERMIDIS AND E. COLI
LUKE WEARDEN GRADE 11 CENTRAL CATHOLIC HIGH SCHOOL
PROBLEM
How do fracking chemicals influence the survivorship of Escherichia coli and Staphylococcus epidermidis?
FRACKING BACKGROUND
• Use: accesses natural gas found in subterranean shale
• Fracking is effective in obtaining energy, but can be harmful to the environment
• Many environmentalists groups including the EPA have taken strong anti-fracking stances
• Are living organisms at risk from fracking?
HOW FRACKING WORKS
FRACKING SOLUTION
Chemical
Sodium Chloride
Calcium Chloride
Magnesium Chloride
PotassiumChloride
Barium Chloride
Strontium Chloride
Amount(mg/L)
75.65 16.65 0.475 0.3846 0.1857 0.20
GRAM (-) VS. GRAM (+) BACTERIA
• Cell wall contains an extra layer of lipopolysaccharides for extra protection.
• Outer membrane protects bacteria from several antibiotics.
• Most pathogenic bacteria in humans are Gram (+) organisms.
• Simple cell wall.• Some antibiotics
work against the formation of the cell wall.
STAPHYLOCOCCUS EPIDERMIDIS (STAPH)
Common surface symbiont in many mammals (Human).
Gram (+) bacteria
Most strains considered non-pathogenic.
Pathogenic strains can be life-threatening.
ESCHERICHIA COLI (E.COLI)
Large and diverse group of gram (-) bacteria
Free living, symbionts, or pathogens
Live in the intestinal tract of many mammals.
Most strains are not pathogenic
Serve as a common prokaryotic cell model.
PURPOSE
Assess the effects of fracking chemicals on the survivorship of Staphylococcus epidermidis and Escherichia coli.
HYPOTHESES
Null Hypothesis: There will be no significant effect of fracking chemicals on the survivorship of E.coli and Staph.
Alternative Hypothesis: The fracking chemicals will significantly reduce the survivorship of the bacteria.
MATERIALS• Fracking Chemicals• Micro and Macro pipettes + Sterile tips• Spreader bars• LB agar plates (1% Tryptone, 0.5% Yeast extract, 1% NaCl)• Escherichia coli DH5-alpha(E.Coli) • Staphylococcus epidermidis• Burner• Sidearm Flask• Vortex• Incubator• Gloves/goggles• SDF (Sterile Dilution Fluid 10 mm KH2PO4, 1 mm MgSO4, 0.1 mm CaCl2, 100 mm
NaCl)• 20 Sterile Test Tubes• Ethanol • Luria Broth Agar Plates(To be Infused with Agar Plates)• 0.22 micron syringe filters and 10mL syringe• Klett Spectrophotometer
PROCEDURE1. Bacteria (E.coli and Staph) were grown overnight in
sterile LB Media.
2. Samples of the overnight cultures were added to fresh media in a sterile sidearm flask.
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.
5. The fracking chemicals were sterilized by means of a 0.2 micron syringe filter
6. The experimental variables were mixed with the appropriate amounts of SDF to create concentrations of 0%, 0.01%, 0.1%, 1%.
CONCENTRATION CHARTIngredients 0% 0.01% 0.1% 1%
Sterile Fluid added
1mL 0.999mL 0.99mL 0.9mL
E.coli/Staph
0.1mL 0.1mL 0.1mL 0.1mL
Fracking Chemicals
0mL 0.001mL 0.01mL 0.1mL
Original Sterile Fluid
8.9mL 8.9mL 8.9mL 8.9mL
Total Volume
10mL 10mL 10mL 10mL
PROCEDURE
7. 100 µL of cell culture was then added to the fracking chemical solutions, yielding a final volume of 10 mL and a cell density of approximately 103 cells/mL.
8. The solutions were vortexed and allowed to sit at room temperature for 15 minutes.
9. After vortexing to evenly suspend the cells, 100 µL aliquots were removed from the tubes and spread on LB-agar plates.
10. The plates were incubated at 37°C for 24 hours.
11. The resulting colonies were counted visually. Each colony was assumed to have arisen from one cell.
ANOVA AND DUNNETT’S TEST
•ANOVA• Statistical test that allows the comparison of means
of different groups
• Dunnett’s Test• Comparison of experimental and control group to
determine significant variation
DATA P-value: 5.472E-28P-value: 2.994E-28
Control 0.01 0.1 10
50
100
150
200
250
300
350
400
450
500
Fracking Fluid Effects of E. coli and Staph
E. ColiStaph
Concentration (percent of Fracking Fluid)
Nu
mb
er o
f S
urv
ivin
g C
olo
nie
s
DUNNETT'S TEST – E. COLI
Concentration T-value Significance
0.01% 2.46 Significant
0.1% 3.77 Significant
1% 4.57 Significant
T-crit = 2.365
DUNNETT’S TEST - STAPH
Concentration T- Value Significance
0.01% 2.69 Significant
0.1% 3.77 Significant
1% 4.58 Significant
T-crit =2.365
CONCLUSIONS
Reject the null hypothesis that fracking chemical will not have a significant effect of Staph and E. coli survivorship. At every concentration for both bacteria the fracking fluid significantly reduced survivorship.
Accept the alternate hypothesis that fracking fluid will have a significant effect on Staph and E. coli survivorship.
An increase in the concentration of fracking fluid will generally correlate with a significant decrease in the survivorship of Staph and E. coli.
LIMITATIONS
Plating was slightly unsynchronized
Only 4 concentrations were tested
Only one exposure time was used
Only one method of exposure used
FUTURE STUDIES
Use a wider variety of concentrations of fracking fluid
Vary exposure times
Use various cell models
Test for synergistic effects
REFERENCEShttps://fracfocus.org/chemical-use/what-chemicals-are-used
http://www.huffingtonpost.com/news/fracking-chemicals/
https://etd.ohiolink.edu/ap/10?0::NO:10:P10_ACCESSION_NUM:osu1366292190
http://onlinelibrary.wiley.com/doi/10.1002/etc.2619/abstract?deniedAccessCustomisedMessage=&userIsAuthenticated=false
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2807625/
http://www.webmd.com/a-to-z-guides/e-coli-infection-topic-overview
Recommended