Inorganic Fertilizer Effects on Yeast John Hollihan Grade 9 Pittsburgh Central Catholic High School 3rd Year in PJAS
Problem Does ammonium phosphate found in inorganic fertilizer have an effect on Saccharomyces cerevisiae, also known as yeast?
Ammonium Phosphate (NH4)3PO4 Chemical compound Salt of ammonium and phosphate Used inorganic fertilizers to increase growth
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
Purpose The purpose of this experiment is to test the effects of ammonium phosphate found in inorganic fertilizer on yeast survivorship.
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.
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
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.
Test Tube Concentrations 0% (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
P-Value for all data=<10-6 0% 0.01% 0.1% 1%
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
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
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
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
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
Bibliography https://www.reference.com/science/chemical- formula-ammonium-phosphate-8861d53094764228 https://www.ihs.com/products/ammonium- phosphates-chemical-economics-handbook.html http://m.jove.com/#details/5081
ANOVA (Single Factor) Results