Bacillus cereus confirmation.

lars albert_63 at hotmail.com
Mon Jan 3 05:08:36 EST 2000


dazzler wrote:
> What confirms B.cereus? Is it the position of the spore or the presence of
> lipid globules in vegetative cytoplasm or both? How many colonies should you
> choose to stain?
> 
> Do other Bacillus species have same appearance on PEMBA and stain in a
> similar fashion? Has anyone had experience with this? Look forward to your
> responses.
> 
> dazza

At least two other species of Bacillus are similar to Bc; B.
thuringiensis and B. anthracis! This group (the B. cereus-group) can be
identified by the use of PCR of the 16S-23S spacer-region (Jensen, M.A.,
J.A. Webster, and N. Straus. 1993. Rapid identification of bacteria on
the basis of polymerase chain reaction-amplified ribisomal DNA spacer
polymorphisms.  Appl.Environ.Microbiol. 59:945-952) - it is very easy
and gives four distinct bands (240, 460, 530, 650bp). To differentiate
between the members of the B.cereus-group you have to look for
plasmid-encoded functions (e.g. the insect toxins encoded by Bt, seen as
crystal-inclusions beside the spore in phase-microscopi or detected by
PCR, or the typical Ba capsule or PCR-primers against some of the
virulence factors (I hope you do not have Ba).

Best wishes

Lars



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