The Effects of Tea Tree Oil and Urea on Escherichia Coli Bacteria Colonies

The purpose of this experiment was to compare the effectiveness of two natural disinfectants, urea and tea tree oil, at three concentrations, high, low, and standard, to determine the percent reduction of Escherichia Coli (E. coli) bacteria colonies.  The experiment consists of preparing the petri dishes in a sterile environment for the application of treatment of high, standard and low values of tea tree oil and urea.  Following treatment, bacteria inoculation takes place by first diluting the concentration of bacteria in three one-milliliter tests tubes and then pouring the bacteria into the petri dish.  The dishes are then placed in an incubation chamber for two days.  The dishes are removed from the incubation chamber and the colonies then counted.  It was determined that tea tree high, 0.55 milliliters of tea tree oil and 0.45 milliliters of distilled water, overall, inhibited the most E. coli bacteria colonies with an average of 20% inhibition.  It was also determined that urea high, 0.135 grams per 10 milliliters of distilled water, was the least effective inhibitor of E. coli bacteria colonies because it averaged approximately 1600% increase in the amount of bacteria found in the Petri dishes.

Research Done By:

Lyndsey Reich
Lakeveiw High School

Tamim Shaker
Sterling Heights High School