E. Coli Lab Report

Plasmids are extra chromosomal DNA within some bacteria that exist as circular structures. Although they are not essential for survival of the bacterium, they often do confer many environment advantages such as antibiotic resistance. One bacteria of interest is E. coli, a gram-negative organism that is part of normal human gut flora. Some strains of E. coli are pathologic to humans, however some strains are beneficial. For example, one strain produces vitamin K, an essential nutrient. In this experiment, E. coli was introduced to two plasmids: pUC18 and lux. Plasmid pUC18 contains a gene that codes for the enzyme beta-lactamase which renders ampicillin and some other antibiotics inactive. Plasmid lux found in V. fischeri contains an operon that codes for luciferase, an enzyme that is involved in a light creating reaction. Within this experiment CaCl2 was used to increase E. coli’s ability to take up plasmids. Once E. coli was able to take up pUC18 and become resistant to ampicillin lux was used to identify E. coli through its light-emitting reaction. The results of this …show more content…
Three agar plates were labeled, each containing the type of treatment, TA name, class section and group number. With a sterile pipet 130 µL mixed bacterial suspension were removed from the tube labeled “C” and the lid from the control was removed, as well as the bacteria dispensed onto the agar. A cell spreader was dipped in ethanol and was used to spread the bacteria evenly along the agar surface. The transfer of 130 µL of bacterial suspensions from the “lux” tube was placed into the “lux” plate and the cells were spread onto the agar surface once again. The cells in the “NP” tubes were plated onto 2 plates labeled “NP” and the lids were replaced with new ones; the plates were left out in room temperature so the liquid could be absorbed within 10 minutes. The plates were inverted and incubated at