Cultivation of E. coli at lower temperature

[Andreas Savelsbergh]

Hi all,

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?

Thanks,

Andreas