Trond Erik Vee Aune wrote:
>>> Tom Knight wrote:
>>> Trond Erik Vee Aune
>> <trondaun at biotech.REMOVETHISBEFOREREPLYING.ntnu.no> writes:
>>>>> other different bacteria, I streaked it onto a new plate. For some
>>> reason it did not come up as a continous smear, but as distinct
>>> colonies, even where I had put a large amount of colony material. And
>>> more surprising, it even came up at places where I had not streaked. I
>>> tried it again, and this time I shook the needle before streaking to
>>> try to remove possible spores. When streaking, I made sure to keep the
>>> needle close to the surface of the agar. Despite of all these efforts,
>>> new colonies grew up up to 1,5 cm away from the area where I had put
>>> the colony material. And still no continous growth, almost like they
>>> are inhibiting themselves.
>>>>>>>> I presume you tried culturing one of your plates without streaking
>> anything on it... If not, and you get colonies on it, then this
>> sounds like your autoclave needs fixing.
>>> It's not contamination. I have full control of my plates. And the
> colonies I get only come up around where I streak the bug. Som it's a
> polar effect.
>> Trond Erik
>
I must admit that the first thing I thought of was contamination. I
would incubate an uninoculates plate from the same batch too.
I assume your loop or wire (if that's what you're using) is not too hot
when you streak out your bacteria? Otherwise, the media or conditions in
which you're growing them may not be suitable. Maybe you could try some
other combinations.
Do you dry your plates before using them? Lots of motile bugs will swim
away from where you streak them (i.e. lots of spirochaetes, Proteus etc)
but usually they dont swim away to form discrete colonies. But it may be
possible. You're plate doesnt even have to be actually wet - even if it
is moist enough they can do it.
How much bigger than E. coli are they? Are they bigger, but still
bacteria sized (rather than yeast or fungus sized).
--
Scott J. Coutts
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