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April 5, 2000


carefull folks


- http://www.agbioworld.org, http://agbioview.listbot.com

At 10:54 AM 3/4/00 -0700, you wrote:
> - http://www.agbioworld.org, http://agbioview.listbot.com
>We need to be careful about such mistakes as the following one
>(below): B. thuringiensis and B. anthracis are not the same
>species. They are in the same GENUS, Bacillus.
Some microbiologists now think that they are the same species and that they
differ only by which plasmids they contain. But I am not an expert on
Bacillus taxonomy. Maybe this idea has been dismissed. But a report in New
Scientist suggested that scientists do believe they may be the same species

Agaisse H, Gominet M, Okstad OA, Kolsto AB, Lereclus D (1999) PlcR is a
pleiotropic regulator of extracellular virulence factor gene expression in
Bacillus thuringiensis. Mol Microbiol 32:1043-1053
Abstract: Members of the Bacillus cereus group (B. anthracis, B. cereus, B.
mycoides and B. thuringiensis) are well-known pathogens of mammals (B.
anthracis and B. cereus) and insects (B. thuringiensis). The specific
diseases they cause depend on their capacity to produce specific virulence
factors, such as the lethal toxin of B. anthracis and the Cry toxins of B.
thuringiensis. However, these Bacillus spp. also produce a variety of
proteins, such as phospholipases C, which are known to act as virulence
factors in various pathogenic bacteria. Few genes encoding these virulence
factors have been characterized in pathogenic Bacillus spp. and little is
known about the regulation of their expression. We had previously reported
that in B. thuringiensis expression of the phosphatidylinositol-specific
phospholipase C gene is regulated by the transcriptional activator PlcR.
Here we report the identification of several extracellular virulence factor
genes by the virtue of their PlcR-regulated expression. These
PlcR-regulated genes encode degradative enzymes, cell-surface proteins and
enterotoxins. The PlcR- regulated genes are widely dispersed on the
chromosome and therefore do not constitute a pathogenic island. Analysis of
the promoter region of the PlcR-regulated genes revealed the presence of a
highly conserved palindromic region (TATGNAN4TNCATA), which is presumably
the specific recognition target for PlcR activation. We found that the plcR
gene is also present in and probably restricted to all the members of the
B. cereus group. However, although the polypeptide encoded by the B. cereus
PlcR gene is functionally equivalent to the B. thuringiensis regulator, the
polypeptide encoded by the B. anthracis gene is truncated and not active as
a transcriptional activator. PlcR is the first example described of a
pleiotropic regulator involved in the control of extracellular virulence
factor expression in pathogenic Bacillus spp. These results have
implications for the taxonomic relationships among members of the B. cereus
group, the virulence properties of these bacteria and the safety of B.
thuringiensis-based biopesticides

Carlson CR, Johansen T, Kolsto AB (1996) The chromosome map of Bacillus
thuringiensis subsp. canadensis HD224 is highly similar to that of the
Bacillus cereus type strain ATCC 14579. FEMS Microbiol Lett 141:163-167
Abstract: A physical map of the Bacillus thuringiensis subsp. canadensis
HD224 chromosome based on AscI, NotI, and SfiI restriction sites has been
established. The chromosome map of 4.3 Mb was similar to a revised map of
the chromosome of the B. cereus type strain ATCC 14579, except that the B.
thuringiensis subsp. canadensis HD224 chromosome lacked a NotI site and had
two additional AscI sites. The positions of 27 probes were identical in the
common macromap. A probe for the insecticidal toxin gene, cryIA, hybridized
only to the B. thuringiensis subsp. canadensis HD224 chromosome. The BssHII
ribotype patterns were almost identical confirming the similarity between
the two strains

Dr Roger Morton 02 6246 5069 (ph)
CSIRO Plant Industry 02 6246 5000 (fax)
GPO Box 1600 roger.morton@pi.csiro.au