1. Inorganic Fertilizer Effects on Yeast
John Hollihan
Grade 9
Pittsburgh Central Catholic High School
3rd Year in PJAS

2. Problem
Does ammonium phosphate found in inorganic fertilizer have an effect on Saccharomyces cerevisiae, also known as yeast?

3. Ammonium Phosphate (NH4)3PO4
Chemical compound
Salt of ammonium and phosphate
Used inorganic fertilizers to increase growth

4. Yeast Saccharomyces cerevisiae Easy to manipulate
Most commonly studied cell
Has similar reproduction, metabolism, and chemistry as other more advanced eukaryotic cells, like human cells.
Was used as a model of other microbial life in soil in this experiment

5. Purpose
The purpose of this experiment is to test the effects of ammonium phosphate found in inorganic fertilizer on yeast survivorship.

6. Hypotheses
Null Hypothesis: The ammonium phosphate will not have a significant effect on yeast survivorship.
Alternative Hypothesis: The ammonium phosphate will significantly alter yeast survivorship.

7. Materials Saccharomyces cerevisiae (Yeast) Burner Micro Tubes
10% Ammonium Phosphate Stock
Micropipettes
Sterile water
Tube Rack
Sterile Fluid (10 mM KH2PO4, 10mM K2HPO4, 1mM MgSO4, 0.1mM CaCl2, 100mM NaCl)
YEPD Agar Plates (1% yeast extract, 2% peptone, 2% dextrose)
Sterile pipette tips
Vortex
Incubator
Spreader Bars
Ethanol

8. Procedure Saccharomyces cerevisiae was grown overnight.
They continued to grow the next morning until they reached a cell density of 107 cells/mL
The following ingredients were mixed together to create the desired concentrations.
The tubes were then incubated at room temperature for 20 minutes.
The tubes were then vortexed and 0.1 mL were plated onto YEPD agar plates.
The plates were incubated for 2 days at 30 degrees Celsius.

9. Test Tube Concentrations0%
(control)
0.01%
0.1% 1%
Sterile Fluid
8.9mL
Ammonium Phosphate
0mL
0.01mL
0.1mL
1mL
Sterile Water
0.99mL
0.9mL
Yeast

10. P-Value for all data=<10-6
0% % % %

11. ANOVA/Dunnett's Test ANOVA (Analysis of Variance) Dunnett's Test
Allows for the comparison of multiple means
Utilize p-values as measures of significance
P>0.05—not significant
P<0.05—significant
Dunnett's Test
ANOVA follow up, localizes source of variation.
Uses a t-value and a t-critical value. If the t-value is greater than the t-critical value, results are considered to be significant
Dunnett's Test Equation

12. Dunnett's Test Results 0.01% 0.1% 1%
Concentration of Ammonium Phosphate
T-Value
Result t-critical=2.94
0.01%
6.67
Significant
0.1%
15.1 1%
1.33
Not significant

13. Interpretation of Results
The null hypothesis can be rejected
The alternative hypothesis can be supported
The ammonium phosphate significantly altered the yeast survivorship
Specifically, it had an effect at 0.01% and 0.1% concentrations

14. Limitations & Inconsistencies
Slightly desynchronized plating
Limited concentration exposures
Only survivorship was tested; not the growth or other health parameters
Only one exposure time was used

15. Extensions Testing more than one microbe
Test survivorship with other concentrations
Use other exposure times to tubes
Agar plate infusion
Other chemical compounds besides ammonium phosphate could be tested
Use other chemical compounds alongside ammonium phosphate to see if there is an interaction

16. Bibliography
formula-ammonium-phosphate-8861d
phosphates-chemical-economics-handbook.html

17. ANOVA (Single Factor) Results