[2] Bacteriophage-mediated generalized transduction in Escherichia coli and Salmonella typhimurium

This chapter discusses the bacteriophage-mediated generalized transduction in Escherichia coli and Salmonella typhimurium. Phage-mediated transduction is one of three ways, along with conjugation and transformation, by which DNA is transferred from one bacterium to another. In transduction, bacterial DNA is encapsidated into phage particles during lytic growth of the phage in the donor cell and is transferred with near unit efficiency to the recipient cell by infection. There it either undergoes recombination with the host chromosome to produce a stable transductant or remains extra chromosomal and gives rise to an abortive transductant. Based on the mode of production of transducing DNA and the means by which it is incorporated into the recipient cell chromosome, transduction can be classified into one of two types—specialized or generalized. In specialized transduction the DNA present in phage is produced by aberrant excision of prophage DNA and, therefore, contains chromosomal sequences adjacent to the prophage DNA as well as prophage sequences. In contrast, generalized transducing particles contain only host chromosomal sequences that are packaged from random or specific sites in host chromosomes.