The Effect of Ethyl Alcohol Concentrations on the Bacteria Decay of
Staphylococcus Epidermidis and Micrococcus Luteus

The objective of our experiment was to determine which concentration of alcohol, 40%, 60% or 80%, would affect the bacteria growth or decay the greatest. Bacteria were grown in starter Petri dishes or Agar. The bacteria were spread onto twenty-four different Petri dishes. Original numbers of bacteria colonies were counted. Ethyl alcohol was diluted down from 95% alcohol to create the three different solutions. The alcohol was soaked onto coffee filter hole-punches and inserted into each Petri dish. After the alcohol treated hole punches were inserted, bacteria colonies were counted every day. Multiple two sample t-tests were run on the data. The results of the tests showed that there was no significant difference in the change in alcohol concentration. The null hypothesis that stated the mean percentage of bacteria colonies grown for 40%, 60% and 80% are all equal. We failed to reject the null hypothesis.  From the data it can be stated that the multiple alcohol concentrations do not have significantly different affects on the growth of bacteria colonies.

Research Done By:

Anna Salvaggio
Warren Mott High School

Howard Stowe
Cousino High School