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Journal of Bacteriology, June 1999, p. 3536-3541, Vol. 181, No. 11
Department of Biological Sciences, University
of Calgary, Calgary, Alberta, Canada T2N 1N4
Received 6 April 1998/Accepted 22 March 1999
Salmonella typhi is the only species of
Salmonella which grows exclusively in humans, in whom it
causes enteric typhoid fever. Strains of S. typhi show very
little variation in electrophoretic types, restriction fragment length
polymorphisms, cell envelope proteins, and intervening sequences, but
the same strains are very heterogeneous for ribotypes which are
detected with the restriction endonuclease PstI. In
addition, the genome of S. typhi has been proven to undergo
genomic rearrangement due to homologous recombination between the seven
copies of rrn genes. The relationship between ribotype
heterogeneity and genomic rearrangement was investigated. Strains of
S. typhi which belong to 23 different genome types were
analyzed by ribotyping. A limited number of ribotypes were found within
the same genome type group; e.g., most strains of genome type 3 belonged to only two different ribotypes, which result from
recombination between rrnH and rrnG operons.
Different genome type groups normally have different ribotypes. The
size and identity of the PstI fragment containing each of
the seven different rrn operons from S. typhi
Ty2 were determined, and from these data, one can infer how genomic
rearrangement forms new ribotypes. It is postulated that genomic
rearrangement, rather than mutation, is largely responsible for
producing the ribotype heterogeneity in S. typhi.
0021-9193/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Role of Genomic Rearrangements in Producing New
Ribotypes of Salmonella typhi
and
*
Corresponding author. Mailing address: Department of
Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4. Phone: (403) 220 6792. Fax: (403) 289 9311. E-mail:
kesander{at}ucalgary.ca.
Present address: Department of Medical Biochemistry, University of
Calgary, Calgary, Alberta, Canada T2N 1N4.
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