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weird bacteria

Graham Shepherd muhero.nospam at globalnet.co.uk
Mon Mar 3 17:44:02 EST 2003

"Scott J. Coutts" <scott.coutts at med.monash.edu.au> wrote in message
news:3E62F0A3.4050407 at med.monash.edu.au...

> But if it's a swarmer and a non-swarmer, why would the discrete colonies
> appear all over the plate? Can swarmers 'carry along' non-swarmers?! If
> the plate is inoculated at only one point, then the swarmers will
> spread, and single colonies of the other one will only be at the
> inoculation point, surely?

I'm not sure from Trond Erik's description exactly what plating technique
he's using, and the appearance of the plate doesn't help much with that. I
would speculate that it might be possible for a non-motile organism to be
carried some distance but a motile one. I hope some of you are going to look
at the plate (especially the magnified view) and tell us what you think.

We don't know much about how dry the plates are, what incubation temperature
and time are being used and so on. They're geneticists who are presumably
handling a small range of well characterised bugs. They're seeing something
they haven't seen before, and are not geared up for isolating pure strains
from difficult mixtures.

> To seperate out our highly motile spirochaetes from other contaminants,
> we cut a slice in the agar, and inoculate the slice. Only our
> spirochaetes are motile enough to get out of there. I'm sure there's
> lots of others that could get out too, but thankfully, we never get them
> as contaminants (: But then, we also have the 'cheats' method of
> separating our spirochaetes - they get through a 0.2um filter, others
> dont (:

My suggestion was based on the types of procedure we know they have
available - I have assumed that their media are obtained ready to use - ie
they don't pour plates or make broth tubes. The ways that microbiologists
would use to do these separations (including Anne's 6% agar) may be
inaccessible to them.

I've only ever worked with dead spirochaetes, but since they were T.
pallidum, it was a satisfactory arrangement.


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