E. Coli Lab Report

The hypothesis tested was that if the incubation temperature of Escherichia coli is lower or higher than 37°C, the amount of bacterial growth will decrease. The results of the plates which experienced growth without contamination supported the hypothesis. The plate incubated at 4°C was contaminated, and therefore the E. coli colonies present on the plate, if any, could not be counted. The plate incubated at 23°C had no growth, which supported the hypothesis that if E. coli was incubated at temperatures higher or lower than 37°C, no growth would be present. The bacterium did not begin to have any uncontaminated growth until the incubation temperature was set to 37°C, which had 71 noticeable E. coli colonies. The plate incubated at 42°C had 68 colonies on the plate, which is less than the 71 …show more content…
coli is considered a mesophile, meaning it grows at moderate temperatures, between 20°C and 40°C, with its optimal growth temperature being 37°C (Piispanen, 2017, Fall Lecture). The results demonstrates that 37°C is the most optimal temperature for growth, as this plate had the highest number of colonies present. However, to support this statement of E. coli being a mesophile, there would had to have been growth on the plate incubated at 23°C. To clarify these findings further and investigate why there was no growth on the 23°C, the experiment could be performed an additional time. However, the sample could be diluted more, using a dilution other than 10-6, such as 10-8. By using a more diluted sample, the number of colonies may be less plentiful, thus allowing for an easier count of the colonies on each plate or possibly only allowing for growth on the 37°C, as it is suggested to be the most optimal temperature for growth (Piispanen, 2017, Fall Lecture). By decreasing the number of bacterium in the starting dilution, it may allow only the plate incubated at the optimal temperature of 37°C to produce colonies, and restricting the other plates incubated at other