[Microbiology] Re: Problems with E. Coli

apurva_micro At yahoo.co.in via microbio%40net.bio.net (by apurva_micro At yahoo.co.in)
Mon Dec 11 11:01:24 EST 2006

Nachiket Vaze wrote:
> Hi.
>     I am a grad student in Bioengineering working on a sterlization project.
> The method that I use for judging the extent of sterlization is the Plate
> Count method. Since I have NO undergrad background in Micro, I am
> struggling. I have a few questions to ask, so please bear with me.
> Q1) After one experiment I found 2 types of colonies growing on the plate.
> One was distinct E. Coli like ( round and whitish) The other was like
> smudge, but with distinct colonies. So I used EMB agar to test them and to
> my surprise, The smudge colonies gave a green sheen and the E. COli looking
> colonies did not. How is that possible?
> Q2) Another weird thing is that I had streaked an EMB late from an isolated
> E. COli colony a few days ago and the plate did show Green sheen but after I
> taped it and kept it in the fridge for a few days, the sheen disappeared. Is
> that supposed to happen.
> Q3) My lab is looking at different methods to judge the degree and the
> mechanism of Sterlization i.e. microbial killing. Can anyone suggest
> something other than Plate Count.
> PLEASE help!!!
> Thanks,
> Nachi
Dear Nachi E.Coli wont be a good indicator for sterilization
testing,since many g+ve spore forming bact. are presant in air.you
might be know one fact is that only 1% of bacteria are culturable in
normal way.colony characters are not used to identify the bact. it is
presumbly understandable.many advance chromatography/ spectroscopy
tech. available to identify the presence of organism on/in objects.

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