Chloramphenicol Resistance Lab Report

Using the P22 phage, a lysate was prepared for the transduction of chloramphenicol resistance from a resistant S. typhimurium LT2 strain to a sensitive strain of S. typhimurium. It is believed that P22 phages package 44 kb of chromosomal DNA at random with a 2% frequency and a 2% chance of homologous recombination events occurring (MIC302 lab manual). S. typhimurium has a chromosome length of approximately 4,857 kb, so it was calculated that 0.00036% is the percent chance that the gene for chloramphenicol resistance will be transduced into the recipient non-resistant S. typhimurium strain’s chromosome. Using an MOI of 0.01, it was determined that 7µl of phage and 100µl of the cells were needed for the transduction. Results of cell and phage growth on LB-CM media …show more content…
It is understood that P22 packages approximately 44 kb of chromosomal DNA randomly and the chromosome in question for this experiment is about 4.8 Mb (4,800 kb). A prediction was made that if P22 packages 44 kb of chromosomal DNA randomly, and S. typhimurium has a chromosome size of about 4,857 kb in length and P22 packages chromosomal DNA mistakenly at a 2% rate in addition to a 2% frequency of homologous recombination, then there is a 0.00036% chance that the gene for chloramphenicol resistance will be added into the recipient non-resistant S. typhimurium strain’s chromosome. In order to run this experiment, a phage lysate was prepared by growing the chloramphenicol resistant S. typhimurium with the P22 phage. The P22 lysate is used to infect the recipient non-resistant strain of S. typhimurium, and considering that very few transductants will contain the gene of interest, specific media was used to select for this. It is important to note that phages containing their own DNA will undergo the lytic cycle, but the phages that contain the bacterial chromosome will not undergo this cycle since they do