Analysis of rRNA restriction fragment length polymorphisms from Bacteroides spp. and Bacteroides fragilis isolates associated with diarrhea in humans and animals.
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1992-04
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Authors
Smith, C. Jeffrey
Callihan, Donald R.
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East Carolina University
Abstract
The Escherichia coli rRNA operon rrnB was used as a 32P-labeled hybridization probe in Southern blots of
genomic DNAs from representative strains of the saccharolytic, gram-negative, obligate anaerobes of the genus
Bacteroides. Control experiments with the B. fragilis type strain ATCC 25285 established that nearly identical
rRNA fragment patterns were produced when either the E. coli rrnB gene probe or homologous rRNA isolated
from B. fragilis was used as the probe. In addition, it was shown that a specific 16S or 23S rrnB gene probe also
could be used to produce fragment patterns suitable for analysis. Thirty-one strains from 8 of the 10 recognized
Bacteroides species were then examined. The resulting autoradiographs revealed specific fragment patterns for
all but one (B. ovatus) of the species tested. Restriction fragment length polymorphisms were observed for many
of the strains tested, but these differences did not hinder species classification. The five B. ovatus strains
examined did not form a distinct group, and their rRNA fragment patterns displayed a marked heterogeneity.
The same approach was applied to a unique set of enterotoxin-producing B. fragilis strains isolted from
animals and humans with diarrhea. The results demonstrated that these strains were in fact B. fragilis and that
they produce rRNA fragment patterns closely related to those of the type strain ATCC 25285. This set of strains
did not appear to form a separate subgroup or genotype within the B. fragilis species, and there were no
distinguishable restriction fragment length polymorphisms that could be used to specifically separate
enterotoxin-producing strains from nonenterotoxigenic strains. Originally published Journal of Clinical Microbiology, Vol. 30, No. 4, Apr 1992
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Journal of Clinical Microbiology; 30:4 p. 806-812