The possible role of recombination in the infection of competent Bacillus subtilis by bacteriophage deoxyribonucleic acid

Recombination data and the kinetics of infection suggest that recipient bacteria are infected by two or more DNA fragments to yield complete phage particles.

Abstract

Bacteriophage SPO-1 will infect a transformable strain of Bacillus subtilis. SPO-1 contains 5-hydroxymethyluracil in place of thymine but is distinguishable from another phage containing this unusual base, SP8, by its host range and serological specificity. DNA extracted from the phage by phenol treatment induces the production of complete phage when added to a competent B. subtilis culture. Mutants of SPO-1 were isolated, and recombination frequencies were determined with whole phage and with infectious DNA. Recombination frequencies were much higher when infection was with DNA rather than with whole phage. Some single bursts giving only recombinant progeny were obtained after infection with a mixture of mutant DNA's These recombination data and the kinetics of infection suggest that recipient bacteria are infected by two or more DNA fragments to yield complete phage particles.