Bio 14 Lab Report

In the BIO 14 Lab, we attempted to design a competition experiment that will tell something about the relative fitness of two strains of E. Coli being studied (E939 – the standard strain and E938 – the mutator strain). The specific question that is being addressed in our competition experiment is: At what concentration does the E938 strain coexist with the E939 strain in terms of the numbers of colonies (used to approximate population size) on Agar + Rif plates? Most of our group members actually arrived this question at first independently and upon further discussion found that we all were looking to answer the same question. I arrived at this question after noticing some interesting patterns when attempting make two strains in the simulation coexist. I kept the

In playing with these particular conditions, I found that some conditions could make both strains coexist relatively well in the antibiotic region of the simulation. This experiment is so scientifically interesting in that the results of this experiment should tell us with whether high-mutation rates or low mutation rates impart a competitive advantage to a certain strain in an antibiotic environment. This be applied to predict which strains of bacteria are more likely to thrive when new antibiotics are developed. With the question found, an experimental design was developed to address this question. The first component to address would be what cultures and concentrations of the two strains of E. Coli would needed in the experiment. All of the competition tubes would have the same stock concentration of 109 cells/mL of the E939, and variable concentrations of E938 in the same tubes (either 109, 107, 105, or 103 cells/mL). This thus allows for the control of the E939 and makes the concentration of E938 the independent variable of the experiment (with the dependent variable being the number of colonies of