autoclaving and PEG

Tue Feb 22 12:38:49 EST 1994

>   What yeasts and other bugs, or their spores, do you think
> survive 259oF of wet heat for 30 min?
smithwhi at (Brian Smith-White):
>>The same ones that grow in "black stokers" and gysers.

Sorry to disappoint you Brian, but it even extreme thermophiles cannot take
autoclaving. In addition, they are so well adapted to their strange niche
that they do not pose *any* threat of contamination to standard reagents
(unless you store them at boiling temperature, under several atmospheres of
pressure, in reducing conditions). By the same token, 5M NaCl is perfectly
comfortable for halophiles (second cousins of some thermophiles) but it is
highly unlikely that your stock will be contaminated by these bugs. Thus,
this solution is, for all practical purposes, sterile. Now, I should mention
that if you live near salt flats (which you don't), you may consider it prudent
to autoclave you NaCl solution.
 This reminds me of an interesting phenomenon I observed when I was at U of
Illinois' Micro dept. (specialists in funny bugs). I had a bottle of 10% SDS
that had little red floaters that appeared after about one year of storage.
The strange thing was that these things seemed to get worse until there was
an appreciable quantity of them at the bottom of the bottle. Then they stopped
"growing". I tried to transfer these things to a fresh bottle, but they did
not take. I could not make out much under the scope, but they were like furry
reddish balls. Possibly they were a chemical contaminant that precipitated,
as I think it highly unlikely that anything would grow in such adverse hostile
conditions. BUT, they did appear to grow. Anyone have any idea about what I

Brett Lindenbach

ps I did not autoclave my SDS!

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