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"Patrick" <in_vivo@usa.net> wrote in message
news:db4f87f8.0109252133.34795436@posting.google.com...
> Hi, I use "Buffered Charcoal Yeast Extract Agar" to grow Legionella
> pneumophila. I make the agar plates myself. Recently One thing happens
> very weird and interestingly that instead of growing evenly across the
> plate, the bacteria grow to form a round midsize lawn only at the
> center of my plates, for all tens of plates. Of course I'm confident
> of spreading the bacterial liquid culture evenly throughout plates.
>
> My first thought was that the addition of charcoal into the agar
> somehow changes the surface tension when the agar solidify so that the
> center of the plates is lower geographically. Anybody has met similar
> problems before and any comments? Thank you.
>
> Plus, how much time does a normal Legionella strain usually take to
> form a lawn on the BCYE plates? Overnight or two days or even longer,
> if I spread the bacteria with 150ul of OD600=3.0?

Do you mean you make the agar from basics or is it a complete powder?

If it's the former check that your agar powder is gelling properly as I
have known batches that haven't worked very well and we had to increase the
agar concentration.
If it hasn't happened before look to see what's changed

Dave

I've never seen Legionella grow as a lawn of growth. It could be that there
is too much water in your formula (or not enough agar). Try pouring the
melted agar at a cooler temp - about 50 C.
-- 
John Gentile                                    Rhode Island Apple Group
yjgent@home.com                                      President
 "I never make mistakes, I only have unexpected learning opportunities"

> From: in_vivo@usa.net (Patrick)
> Organization: http://groups.google.com/
> Newsgroups: sci.bio.microbiology,bionet.microbiology
> Date: 25 Sep 2001 22:33:44 -0700
> Subject: weird growth on agar
> 
> Hi, I use "Buffered Charcoal Yeast Extract Agar" to grow Legionella
> pneumophila. I make the agar plates myself. Recently One thing happens
> very weird and interestingly that instead of growing evenly across the
> plate, the bacteria grow to form a round midsize lawn only at the
> center of my plates, for all tens of plates. Of course I'm confident
> of spreading the bacterial liquid culture evenly throughout plates.
> 
> My first thought was that the addition of charcoal into the agar
> somehow changes the surface tension when the agar solidify so that the
> center of the plates is lower geographically. Anybody has met similar
> problems before and any comments? Thank you.
> 
> Plus, how much time does a normal Legionella strain usually take to
> form a lawn on the BCYE plates? Overnight or two days or even longer,
> if I spread the bacteria with 150ul of OD600=3.0?

in_vivo@usa.net (Patrick) wrote:


>Plus, how much time does a normal Legionella strain usually take to
>form a lawn on the BCYE plates? Overnight or two days or even longer,
>if I spread the bacteria with 150ul of OD600=3.0?

Hi Patrick,

we give our Legionella a little bit more time to grow. Usually you can
see small colonies after two days, but it�s better to grow them for
five days. Make sure the humidity in your incubator is high enough.
If there is a ventilator the agarplates run dry and the growth will be
retarded.

Andrea