초록
<P><B>Highlights</B></P><P><I>► Escherichia coli</I> was cultivated at 6–10°C to produce recombinant proteins. ► <I>E. coli</I> strains without cold adapted chaperones grew at the extremely low temperatures. ► The active soluble proteins were produced in large quantity under this condition. ► This strategy is effective for overcoming the insolubility of recombinant proteins.</P> <P><B>Abstract</B></P><P>Protein expression in <I>Escherichia coli</I> at 15–25°C is widely used to increase the solubility of recombinant proteins. However, many recombinant proteins are insolubly expressed even at those low temperatures. Here, we show that recombinant proteins can be expressed as soluble forms by simply lowering temperature to 6–10°C without cold adapted chaperon systems. By using <I>E. coli</I> Rosetta-gami2(DE3), we obtained 1.8 and 0.9mg of <I>Cryptopygus antarticus</I> mannanase (CaMan) and cellulase (CaCel) from 1l culture grown at 6 and 10°C, respectively. Cultivation at 10°C also led to successful expression of EM3L7 (a lipase isolated from a metagenomic library) in a soluble form in <I>E. coli</I> BL21(DE3). Consequently, <I>E. coli</I> cultivation at 6–10°C is an effective strategy for overcoming a major hurdle of the inclusion body formation.</P>