Transduction is the process of transferring the DNA (deoxyribonucleic acid) from one bacteria to another with the help of a bacteriophage. There are two types of transduction; generalized and specialized transduction.
In generalized transduction, the bacteriophage picks up any part of bacterial DNA during the lytic cycle and transfers it into a new bacteria after infecting it. So, virtually any genetic marker can be transferred from donor to recipient cell in this kind of transduction, but it occurs at a low frequency.
A bacteriophage is a type of virus that infects bacteria. In fact, the word “bacteriophage” literally means “bacteria eater,”
Mechanism of Generalized Transduction
To understand the process of generalized transduction, you must first be aware of the lytic cycle of bacteriophage. When a population of a sensitive bacterium is infected with bacteriophage following sequential events occur:
- Attachment/adsorption of bacteriophage to the bacteria
- Penetration of phage DNA
- Replication of phage DNA/RNA
- Synthesis of nucleic acid and proteins
- Assembly of phage protein and nucleic acid
- Release of mature bacteriophage
The process mentioned above is normal, but occasionally, the enzyme responsible for packaging viral DNA into the bacteriophage accidentally packages host DNA.
When the bacterial cell is lysed, these transducing (host DNA within phage coat) particles are released along with normal virions. These defective transducing particles cannot initiate the normal viral infection as they do not contain viral DNA (instead, they have host DNA).
When the lysate containing both normal virions and transducing phage particles are mixed with a sensitive bacterial population, most bacteria get infected with normal virions, and very few bacteria receive DNA from the previous host bacterium.
This DNA now undergoes genetic recombination with the DNA of the new host. They will be lost if the donor genes do not undergo homologous recombination with the recipient bacterial chromosome.
Bacteriophages that form transducing particles can be either temperate or virulent.
Transduction in Bacterial Populations
Transduction is found in a variety of bacterial populations including:
- Escherichia coli
- Pseudomonas spp
- Salmonella spp
- Staphylococcus spp
Difference Between Generalized and Specialized Transduction
Although generalized and specialized transduction is the process of transferring the bacteria genome by the bacteriophage (virus), they have many differences. Firstly, the DNA carried by bacteriophages in generalized transduction can be any part of the genome, but the transduced DNA in specialized transduction is specific.
Likewise, the phage transferring the gene in generalized transduction is virulent or temperate, usually in the lytic cycle. Still, the bacteriophage in specialized transduction is only a temperate phage in the lysogenic cycle. Similarly, in generalized transduction, the host gene combines with the viral genome due to error during assembly, but in specialized transduction, the combination occurs due to error during excision.
Image source: https://commons.wikimedia.org/w/index.php?title=File:Transduction_illustration.pdf&oldid=499048722.
References
- Thierauf, A., Perez, G., & Maloy, a. (2009). Generalized Transduction. Methods In Molecular Biology, 267-286. doi: 10.1007/978-1-60327-164-6_23
- transduction (prokaryotes) | Learn Science at Scitable. (2022). Retrieved 9 August 2022, from https://www.nature.com/scitable/definition/transduction-prokaryotes-292/
- Fields, B., Knipe, D., & Howley, P. (2007). Fields’ virology (6th ed.). Philadelphia, Pa.: Wolters Kluwer Health/Lippincott Williams & Wilkins.
