Conjugation and Transposition in Escherichia Coli
Abstract
The purpose of this experiment was to study the transfer of genetic information on plasmid F’lac by using Escherichia coli. Plasmid transfer was measured by using two different methods. The first one was by using selection and contraselection with three antibiotics: streptomycin(which was replaced by naladixic acid for the second part of the experiment),ampicillin and kanamycin and the second one by using a colour indicator ( X-gal). As significant results, the percentage of transfer for F’lac was higher than the percentage for transposition. Also, the experiment demonstrated that E.coli can quickly acquire resistance to several different antibiotics through the transfer of the F’lac plasmid. It was concluded that significant changes on the genetic makeup can be achieved through transposition and conjugative plasmids in a short amount of time, which can have severe implication on the effectiveness of antibiotics for bacterial diseases.
Introduction
The purpose of this experiment is to study the transfer of genetic information on plasmid F’lac by using the bacteria Escherichia coli. The genome of the bacteria consists of a single circular DNA molecule. Many bacteria also contain plasmids which assist on the transfer of genetic material, in E.coli it is called the fertility factor (F). The donor bacteria containing the F factor are designated F+, whereas the recipient, which usually lacks the F factor are designated F- (Becker et al).
Bacterial conjugation enables the horizontal transfer of plasmids through appendages formed by the F+ called sex pili, which creates the bridges necessary between the donor and the recipient, in order for the process to occur (Bates et al, 1998).
Sometimes transposition can occur with conjugation, this happens when insertion sequences shift from the bacterial chromosome to the plasmid so they can be transferred from the donor to the recipient. (Griffiths et al, 2008)
In the first part of the
The purpose of this experiment was to study the transfer of genetic information on plasmid F’lac by using Escherichia coli. Plasmid transfer was measured by using two different methods. The first one was by using selection and contraselection with three antibiotics: streptomycin(which was replaced by naladixic acid for the second part of the experiment),ampicillin and kanamycin and the second one by using a colour indicator ( X-gal). As significant results, the percentage of transfer for F’lac was higher than the percentage for transposition. Also, the experiment demonstrated that E.coli can quickly acquire resistance to several different antibiotics through the transfer of the F’lac plasmid. It was concluded that significant changes on the genetic makeup can be achieved through transposition and conjugative plasmids in a short amount of time, which can have severe implication on the effectiveness of antibiotics for bacterial diseases.
Introduction
The purpose of this experiment is to study the transfer of genetic information on plasmid F’lac by using the bacteria Escherichia coli. The genome of the bacteria consists of a single circular DNA molecule. Many bacteria also contain plasmids which assist on the transfer of genetic material, in E.coli it is called the fertility factor (F). The donor bacteria containing the F factor are designated F+, whereas the recipient, which usually lacks the F factor are designated F- (Becker et al).
Bacterial conjugation enables the horizontal transfer of plasmids through appendages formed by the F+ called sex pili, which creates the bridges necessary between the donor and the recipient, in order for the process to occur (Bates et al, 1998).
Sometimes transposition can occur with conjugation, this happens when insertion sequences shift from the bacterial chromosome to the plasmid so they can be transferred from the donor to the recipient. (Griffiths et al, 2008)
In the first part of the
References: 3. Bates, S; Cashmore, AM and Wilkins, BM. 1998. IncP Plasmids Are Unusually effective in mediating Conjugation of Escherichia coli and Saccharomyces cerevisiae: Involvement of the Tra2 Mating System. Journal of Bacteriology. 180:6538-6540. 4