Cultivation of E. coli at lower temperature

Cornelius Krasel krasel at wpxx02.toxi.uni-wuerzburg.de
Thu Jul 9 13:29:04 EST 1998


In bionet.molbio.methds-reagnts Andreas Savelsbergh <asavel at uni-wh.de> wrote:
> my own experience and that of lab-fellows says that pre-cultivation of
> E. coli (BL21(DE3)pLysS) for expression cultures of toxic proteins at
> lower temperatures gives sometimes better results (= cells grow) than
> pre-cultivation at 37°C (= cells don't grow). Expression itself
> sometimes is only possible at 30 °C, while at 37°C nothing grows or is
> expressed.
> My question is: Does anybody have a reasonable explanation for that? Are
> there proteases which are less active at lower temperatures. Does
> anybody know a reference for that?

My uneducated guess (no reference, sorry):

Most enzymes are less active at lower temperatures. Furthermore, proteins
may fold more stably at lower temperatures (although this is not always
true; there are also cold-sensitive proteins), and the bacteria have
more time to accommodate to adverse conditions (at 37°C in a well-shaken
culture, E.coli does almost nothing but divide).

--Cornelius.

-- 
/* Cornelius Krasel, U Wuerzburg, Dept. of Pharmacology, Versbacher Str. 9 */
/* D-97078 Wuerzburg, Germany   email: phak004 at rzbox.uni-wuerzburg.de  SP4 */
/* "Science is the game we play with God to find out what His rules are."  */



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