Bacterial Transduction Unveiled A Genetic Tango between Bacteriophages and Bacteria

Bacterial transduction is a sophisticated genetic phenomenon wherein bacteriophages, the viruses that infect bacteria, act as molecular couriers, ferrying bacterial DNA from one cell to another. This elegant process plays a pivotal role in the dynamic evolution of bacterial populations.

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Types of Transduction

1. Generalized Transduction

• Definition: Random bacterial DNA is unintentionally encapsulated into phage particles during the viral replication cycle.
• Procedure: 

• Infection by Bacteriophage:

  • A bacteriophage infects a bacterial cell, injecting its genetic material into the host.

• Replication of Phage DNA:

  • The phage DNA takes over the bacterial cell's machinery, directing it to replicate the viral genome.

• Random Packaging of Bacterial DNA:

  • During the assembly of new phage particles, fragments of bacterial DNA may be mistakenly packaged into the phage capsid.

• Release of Phage Particles:

  • The newly formed phage particles, containing both viral and bacterial DNA, are released from the host bacterial cell.

• Infection of New Bacterial Host:

  • The phage particles infect a new bacterial cell.

• Integration of Bacterial DNA:

  • The bacterial DNA that was mistakenly packaged into the phage enters the new host cell.

• Homologous Recombination:

  • The bacterial DNA integrates into the genome of the new host cell through homologous recombination with the recipient's DNA.

• Expression of New Genetic Material:

  • The integrated bacterial DNA is transcribed and translated by the host cell machinery, leading to the expression of new genetic material.

1. Specialized Transduction

• Definition: Selective packaging of specific bacterial genes, situated near the phage integration site, occurs during phage replication.
• Procedure: 

• Lysogeny:

  • The temperate bacteriophage (a virus that infects bacteria) infects a bacterial cell.
  • Instead of immediately entering the lytic cycle, the phage may integrate its DNA into the bacterial chromosome, forming a prophage.
  • The integrated phage DNA becomes part of the bacterial genome and is replicated along with the bacterial DNA during cell division.

• Induction of the Prophage:

  • Under certain conditions (such as stress), the prophage may be induced to leave the bacterial chromosome and enter the lytic cycle.

• Incorrect Excision of Prophage:

  • During the induction process, the excision of the prophage may be imprecise.
  • Instead of excising only the prophage, adjacent bacterial genes may be mistakenly excised along with the phage DNA.

• Formation of Transducing Particle:

  • The imprecisely excised DNA, which now contains both phage and bacterial genes, is packaged into new phage particles.

• Release of Transducing Particle:

  • The transducing particles, carrying the hybrid DNA, are released from the lysed host cell.

• Infection of New Bacterial Host:

  • The transducing particles infect a new bacterial cell.

• Integration of Transduced DNA:

  • The transduced DNA integrates into the genome of the new host cell.

• Expression of Transduced Genes:

  • The integrated genes are transcribed and translated in the new host cell, leading to the expression of the transduced genetic material.

Bacterial transduction stands as a genetic alchemy, fostering adaptability and diversity among bacterial communities. This phenomenon underscores the intricate relationship between bacteriophages and bacteria, shaping the genomic landscape in unforeseen ways.

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