Abstract:Conjugation is a natural occurring process that involves the transfer of DNA from one cell into another through a physical connection between the cells. In the following experiment, two strains of Escherichia coli bacterial cells (donor F'lac+strs and recipient F-lac-strr) underwent conjugation to produce a transconjugant strain (F'lac+strr). MAC plates and streptomycin were utilized to determine if conjugation had occurred. When plated, the donor colonies appeared red and the recipient colonies appeared white. The transconjugant plates showed red and white colonies. Using alkaline lysis miniprep, a DNA plasmid was isolated from the donor and transconjugant strains and FIGE electrophoresis was used to determine the size of the plasmid. The conjugation efficiency was found to be 16.25% and the plasmid DNA was approximately 97 kilobases long. The results show that the F' plasmid was effectively transferred from the donor cells into the recipient cells via conjugation.
Introduction:Bacterial conjugation is the unidirectional transfer of either genomic DNA or plasmid DNA from a donor bacterial cell to a recipient bacterial cell by cell-to-cell contact via a sex pilus (Snustad & Simmons, 2006).
Conjugation was first discovered by Lederberg and Tatum in 1946. In their experiment, they grew two strains of bacteria in separate vessels with rich medium and then together in one vessel containing the same medium. Then, they spread the three vessel contents onto medium agar plates and incubated them overnight at 37ÃÂC. The only plate that showed cell growth was the plate containing the mixture of the two bacterial strains. The other two plates showed no growth. This experiment proved that in order for recombination to occur, the two strains must come in contact with one another (Lederberg, Tatum, 1946).
In 1950, Bernard Davis discovered that cell-to-cell contact was required to obtain a transconjugant. Using a U tube containing a...