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weird bacteria

Trond Erik Vee Aune trondaun at chembio.NOSPAM.ntnu.no
Sun Mar 2 14:40:15 EST 2003

Scott J. Coutts wrote:

> What do the colonies look like, and how big are they? Would it be 
> possible for you to post some pictures on the web somewhere, or in 
> alt.test

Here's a large picture I took yesterday of the buggers:


Let me explain the picture (a 9 cm plate). If you look carefully at the 
part of the plate furthest away from the camera you'll be able to see a 
thin red line written on the bottom of the plate. This was the boundary 
of the original streaking. I put a fair amount of colony material in 
this area, but the day after only distinct colonies had appeared, and 
too my surprise single colonies also had grown outside this area. For 
each day after this, the colonies spread further down the plate. At 
first they appear to have no connection with the other colonies, but 
after a few days, thin lines seem to connect them (you can probably see 
this between the oldest colonies. The newest colonies (those closest to 
the lens) seem to have no connection to the others). Some of the 
colonies also look like spirals, almost as if they have been built by 
bacteria swimming in a spiral.

So there are two strange things with this bug:

1) They seem not to like growing close. Where I started streaking, only 
distinct colonies appeared. Only occasionally to they grow so close that 
they touch each other. But as time progresses new colonies are forming 
inbetween the older.

2) They spread over the plate. Probably by swimming, but they seem to 
try to reach quite far away before proliferating.

These two points are probably related. Maybe they really are sensitive 
to their own antibiotic, but why would they then survive in colonies?

Btw, I have grown the bug in liquid media, I did not follow the growth, 
but the day after, the culture looked quite ordinary, like E.coli.

Trond Erik

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