We have investigated production, solubility and activity of recombinant glutathione-S-transferase (GST) expressed in Escherichia coli BL21 grown in defined media with glucose or glycerol as carbon source. GST was predominantly expressed as a soluble protein on both carbon sources, and 83-84% was found in the supernatant after cell lysis. In cultures grown on glucose, only 32 +/- 9% of the GST was active, while 76 +/- 13% of the GST was active in cultures grown on glycerol. This shows that glycerol has the potential to increase the activity of soluble GST in E. coli cultures in vivo. (c) 2007 Elsevier Ltd. All rights reserved.