Blog 22: Error

Unfortunately this experiment contained many errors, both human and experimental. One of the human errors was that the experiment was supposed to be based on E. coli breaking down the apples, but instead a different bacteria called Bracillus cereus was used in its place. One major experimental error was that four of the petri dishes from the second batch of agar had been contaminated with foreign bacteria. This brought up question on whether or not the previous petri dishes had also been contaminated. Another problem was that the apple slices had to be placed directly into the agar after they had been soaked which left traces of water in the petri dishes. This causes some inconsistencies is the firmness of the agar. Condensation in the petri dishes posed a problem since they began to dry out at different rates. By the third day of the experiment some of the dishes showed signs that they would dry out completely and it became necessary to seal the edges of the petri dishes. This could affect the final dry mass that was measured.