Freeze-drying E.coli

Ivano de Filippis ivano at ALPHA.INCQS.FIOCRUZ.BR
Mon Mar 22 07:14:45 EST 1999

Even freeze-dried, is not advisable long term store of E.coli at room
temperature. We made a study some years ago with some different bacteria
species, and most of them  (specially gram neg.) didn't survive for long
time at temperatures above 0 C. Some of them also had some physiology changes.
At this temperature the best results you can achieve are by growing them in
stock agar slants, close the tube tight with rubber stopper, and seal them
with paraffine. I know some collections that holds enterobacterias for 15
years with this method.
If you prefer freeze-dry, it's enough to suspend the strains in  a sterile
10% skim milk solution (be careful with autoclavation to avoid the
inactivation of carbohidrates; the solution after sterilization must be
still white; you can reduce sterilization time to keep  this color, but make
sterility tests after that), freeze the ampoules with absolute ethanol and
dry-ice (small volumes of strain suspension, 0.3-0.5ml) and freeze-dry.

Good luck

At 14:10 19/03/99 -0800, you wrote:
>    I would like to store E.coli long term at room temperature. The only way
>I know of doing it is by freeze-drying. Does anyone have any protocols for
>freeze-drying E.coli?
Ivano de Filippis
Fundacao Oswaldo Cruz - FIOCRUZ
Instituto Nacional de Controle de Qualidade em Saude - INCQS
Depto. de Microbiologia
Lab. de Materiais de Referencia
Av. Brasil, 4365 - Manguinhos
Rio de Janeiro - 21045-900 - BRASIL
Tel.: 55-21-598-4290/4291/4292/4293
FAX: 55-21-290-0915
E-mail: ivano at alpha.incqs.fiocruz.br

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