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Updated: Aug 25, 2026

Bacteriophage Removal from Infected Salmonella Cultures
Published on: June 28, 2024
Complete genomic sequence of the virulent Salmonella bacteriophage SP6
Aleisha T Dobbins1, Matthew George, Daryl A Basham
1Department of Biochemistry and Molecular Biology, Howard University College of Medicine, Washington, DC 20059, USA.
Abstract:
We report the complete genome sequence of enterobacteriophage SP6, which infects Salmonella enterica serovar Typhimurium. The genome contains 43,769 bp, including a 174-bp direct terminal repeat. The gene content and organization clearly place SP6 in the coliphage T7 group of phages, but there is approximately 5 kb at the right end of the genome that is not present in other members of the group, and the homologues of T7 genes 1.3 through 3 appear to have undergone an unusual reorganization. Sequence analysis identified 10 putative promoters for the SP6-encoded RNA polymerase and seven putative rho-independent terminators. The terminator following the gene encoding the major capsid subunit has a termination efficiency of about 50% with the SP6-encoded RNA polymerase. Phylogenetic analysis of phages related to SP6 provided clear evidence for horizontal exchange of sequences in the ancestry of these phages and clearly demarcated exchange boundaries; one of the recombination joints lies within the coding region for a phage exonuclease. Bioinformatic analysis of the SP6 sequence strongly suggested that DNA replication occurs in large part through a bidirectional mechanism, possibly with circular intermediates.
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