If Colony plated on plate coming below agar, is it contamination? - (Sep/05/2012 )
If Colony plated on plate coming below agar, is it contamination?
Hi,
When you plate bacteria onto a Medium-Agar plate the bacteria should growth on the surface of the agar, otherwise your plate its contaminated from the time of preparation.
Depends on what you call "below", its hard to tell.
Sometimes people think its "below", while in fact its just an optical "illusion". Or sometimes bacteria can grow into the medium/agar...
Its hard to tell, but if you have doubts (and never seen this before with that specific bacterium) then just trow it out...
I would say yes, contamination.
But just try to isolate them!
pito on Wed Sep 5 19:58:07 2012 said:
Depends on what you call "below", its hard to tell.
Sometimes people think its "below", while in fact its just an optical "illusion". Or sometimes bacteria can grow into the medium/agar...
Its hard to tell, but if you have doubts (and never seen this before with that specific bacterium) then just trow it out...
Its not optical illusion. I collected colony by 1-10ul tip. I have to pierce the gel to reach it. I collected it. It has grown in LB. planning to check it.
prabhubct on Thu Sep 6 12:01:00 2012 said:
pito on Wed Sep 5 19:58:07 2012 said:
Depends on what you call "below", its hard to tell.
Sometimes people think its "below", while in fact its just an optical "illusion". Or sometimes bacteria can grow into the medium/agar...
Its hard to tell, but if you have doubts (and never seen this before with that specific bacterium) then just trow it out...
Its not optical illusion. I collected colony by 1-10ul tip. I have to pierce the gel to reach it. I collected it. It has grown in LB. planning to check it.
Ok
then its most likely contamination.
The next time you prepare your LB plates take one and keep it Overnight at 37°C. If something grows on it discard the rest. This will save you time and money.
pito on Thu Sep 6 15:50:48 2012 said:
prabhubct on Thu Sep 6 12:01:00 2012 said:
pito on Wed Sep 5 19:58:07 2012 said:
Depends on what you call "below", its hard to tell.
Sometimes people think its "below", while in fact its just an optical "illusion". Or sometimes bacteria can grow into the medium/agar...
Its hard to tell, but if you have doubts (and never seen this before with that specific bacterium) then just trow it out...
Its not optical illusion. I collected colony by 1-10ul tip. I have to pierce the gel to reach it. I collected it. It has grown in LB. planning to check it.
Ok
then its most likely contamination.
Can you say what contamination would grow below agar surface? Is it fungi? or bacteria? could they be anaerobic bacteria growing below surface?
i would put my money on fungi 
but you never know unless you spend time to regrow them and do a simple microscopy 
prabhubct on Fri Sep 7 09:03:19 2012 said:
pito on Thu Sep 6 15:50:48 2012 said:
prabhubct on Thu Sep 6 12:01:00 2012 said:
pito on Wed Sep 5 19:58:07 2012 said:
Depends on what you call "below", its hard to tell.
Sometimes people think its "below", while in fact its just an optical "illusion". Or sometimes bacteria can grow into the medium/agar...
Its hard to tell, but if you have doubts (and never seen this before with that specific bacterium) then just trow it out...
Its not optical illusion. I collected colony by 1-10ul tip. I have to pierce the gel to reach it. I collected it. It has grown in LB. planning to check it.
Ok
then its most likely contamination.
Can you say what contamination would grow below agar surface? Is it fungi? or bacteria? could they be anaerobic bacteria growing below surface?
Most likely fungi yes.
Could be a bacterium too.. hard to tell, you would need to look at it under the microscope.