Will lyophilisation kill all bacteria?

I made a protein solution which was supposed to be sterile because I
use it in cell culture experiments. However, it turned out it somehow
got contaminated by bacteria. The solution cannot be autoclaved (this
will irreversibly denature my protein), so I am looking for another
way to get my solution sterile. So my question is:
Will lyophilisation kill all bacteria that got into my solution and
anywhere in the tube?

Regards,
Peter

No, lyophilization is often used to preserve bacteria, rather than to
kill them. I'd recommend sterile filtration with an 0.2u syringe tip
filter.

Very less chance of lyophilization killing bacteria especially if they re
producing spores, as most contaminant bacteria may have arrived there in the
form of spores in the first place.
if bacterial proteins are not a problem would reprecipitation of
proteins with a agent like Ethanol or acetone solve the problem?
Jayakumar



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Filter sterilization is also a good idea. but take care to use filters made
of materials which will not cause the proteins to adhere to the filter.
jayakumar


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On 23 Jul 2003, Wolfgang Schechinger wrote:


smart idea. however, may i suggest not using skimmed milk? it has rather
large (several microns across!) lumps in it which will block the filter.
of course, you could always filter the milk to clear the lumps (i've
successfully used a 0.45 um and a 0.2 um syringe filter in series to do
this, as a 0.2 on its own clogs way too fast; it also helps to centrifuge
the milk first to get rid of really huge bits), then use that to block a
filter, then filter the protein with that.

alternatively, i have heard of FCS being used for blocking. however,
that's (a) expensive and (b) likely to contaminate the protein solution.

on the gripping hand, these filters are designed for minimum protein
binding, so none of this should be necessary.

tom

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