A prophage lambda inserted by homologous recombination near dif, the chromosome dimer resolution site of Escherichia coli, is excised at a frequency that depends on its orientation with respect to dif. In wild-type cells, terminal hyper- (TH) recombination is prophage specific and undetectable by a test involving deletion of chromosomal segments between repeats identical to those used for proph...

The temperature-sensitive mutant CRT46 of Escherichia coli K12 is unable to initiate new rounds of DNA replication at 42 degrees C. Mutants of bacteriophage P2 have been isolated, which, in the prophage state, allow mutant CRT46 to grow at 42 degrees C. The lysogenic bacteria that grow at 42 degrees C are apparently replicating under the control of prophage P2, which substitutes for the bacteri...

The DNA uptake competence (Com) system of the intracellular bacterial pathogen Listeria monocytogenes is considered nonfunctional. There are no known conditions for DNA transformation, and the Com master activator gene, comK, is interrupted by a temperate prophage. Here, we show that the L. monocytogenes Com system is required during infection to promote bacterial escape from macrophage phagoso...

Strains of Haemophilus influenzae that carry a defective prophage are more sensitive to heat than is a strain that does not, even in the presence of a rec-1 mutation, which normally renders prophage noninducible. The prophage of HP1c1, a nondefective phage, does not affect the heat sensitivity.

Both prophage integration in bacteriophage P2 and the reverse event, prophage excision, are known to require a specific phage gene product, the so-called int function. We find that P2 can integrate efficiently at a free attachment site also in an immune host (i.e., in the presence of phage specific repressor) provided the superinfecting phage is not deficient in int function. Prophage P2, on th...

Transformation of competent Bacillus subtilis lysogenic for SP02 with any of three plasmids (pCM194, pUB110, pAM77) generates drug-resistant transformants of which 5 to 20% have lost the infectivity and immunity associated with the SP02 prophage. Such cured derivatives can be again lysogenized with SP02 and again cured by introduction of a different plasmid. Elimination of the SP02 prophage was...

Shiga toxin-producing Escherichia coli (STEC) may cause bloody diarrhea and hemorrhagic colitis (HC), with subsequent systemic disease. Since genes coding for Shiga toxins (stx genes) are located on lambdoid prophages, their effective production occurs only after prophage induction. Such induction and subsequent lytic development of Shiga toxin-converting bacteriophages results not only in prod...

Optical maps for five representative clinical, food-borne and bovine-derived isolates from the 2006 Escherichia coli O157 : H7 outbreak linked to fresh spinach in the United States showed a common set of 14 distinct chromosomal markers that define the outbreak strain. Partial 454 DNA sequencing was used to characterize the optically mapped chromosomal markers. The markers included insertions, d...

Two kinds of prophage deletions of the Salm.onella phage P22 were isolated. One type of deletion was isolated by simultaneously selecting for loss of a host gene (pro) adjacent to the integrated prophage and for survival at the nonpermissive temperature of a temperature-inducible (tse2) lysogen. The second type of deletion was isolated by transduction to tetracycline resistance using high-frequ...