The Effect of Runoff on A. vinelandii

2010 Fairfax County Regional Science and Engineering Fair

The abstract below was written by the student. The Northern Virginia Soil and Water Conservation District made no editorial changes.

The Effect of Runoff on A. vinelandii

by Catie Liebeck, Sophomore, West Potomac High School


This project looks at the effect of urban run off on a soil dwelling bacteria, Azotobacter Vineladii. The original idea was to determine how different house hold acids and bases affected the luminesses of Azotobacter Vineladii and then relate it to the bacteria’s affect on soil. The experiment showed by adding runoff to the bacteria, besides weak acids, will not be able to produce as much light and thereby as humans we are hurting the bacteria by urban run off.

Light out put was determined by means of culturing the bacteria into fifteen plates and then measuring the light amount. The average of the fifteen plates before adding the runoff was 73.8 lux. Next A Strong Acid and Base and Weak Acid and Base were added to three different plates respectively. An additional three plates were not given anything (control). One day after the runoff was given to the bacteria, light out put was again measured: Strong Acid110 lux, Strong Base 32lux, Weak Acid 205 lux, Weak Base 62 lux, and control 147 lux. The use of Strong bases lessened the ability of the Azotobacter Vineladii to produce light while when in contact with a weak acid it increased luminesses.

The contributions of this project show that most runoff, except weak acids will negatively impact Azotobacter Vineladii. If the Azotobacter Vinelandii is compromised by urban runoff then the nutrient level in the soil will decrease, decreasing plant growth and sustainability of the plant.

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