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Applied and Environmental Microbiology, April 1999, p. 1483-1490, Vol. 65, No. 4
Central Research Laboratory,
Received 25 September 1998/Accepted 5 January 1999
As 16S rRNA sequence analysis has proven inadequate for the
differentiation of Bacillus cereus from closely
related species, we employed the gyrase B gene (gyrB)
as a molecular diagnostic marker. The gyrB genes of
B. cereus JCM 2152T,
Bacillus thuringiensis IAM 12077T,
Bacillus mycoides ATCC 6462T, and
Bacillus anthracis Pasteur #2H were cloned and
sequenced. Oligonucleotide PCR primer sets were designed from within
gyrB sequences of the respective bacteria for the
specific amplification and differentiation of B. cereus, B. thuringiensis, and
B. anthracis. The results from the amplification
of gyrB sequences correlated well with results obtained
with the 16S rDNA-based hybridization study but not with the results of
their phenotypic characterization. Some of the reference strains of
both B. cereus (three serovars) and B. thuringiensis (two serovars) were not positive in PCR
amplification assays with gyrB primers. However, complete
sequencing of 1.2-kb gyrB fragments of these reference
strains showed that these serovars had, in fact, lower homology than
their originally designated species. We developed and tested a
procedure for the specific detection of the target organism in boiled
rice that entailed 15 h of preenrichment followed by PCR
amplification of the B. cereus-specific fragment.
This method enabled us to detect an initial inoculum of 0.24 CFU of B. cereus cells per g of boiled rice food
homogenate without extracting DNA. However, a simple two-step
filtration step is required to remove PCR inhibitory substances.
0099-2240/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Cloning and Nucleotide Sequence Analysis of gyrB of
Bacillus cereus, B. thuringiensis,
B. mycoides, and B. anthracis and
Their Application to the Detection of B. cereus in
Rice
*
Corresponding author. Present address: Environmental
Engineering Sciences, California Institute of Technology, Mail Code
138-78, 1200 E. California Ave., Pasadena, CA 91125. Phone: (626)
395-2994. Fax: (626) 395-2940. E-mail:
kjvenkat{at}cco.caltech.edu.
Applied and Environmental Microbiology, April 1999, p. 1483-1490, Vol. 65, No. 4
0099-2240/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
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