A cDNA encoding human liver UDP-glucuronosyltransferase 2B4, which glucuronidates the bile acid hyodeoxycholic acid, has been expressed in Escherichia coli as a fusion protein with Staphylococcus aureus protein A. The expression of this protein, under the control of the thermo-inducible lambda-P-R promoter was induced by a shift in culture temperature. In order to increase both the biomass and the amount of recombinant protein, the temperature profile in the batch culture and especially the influence of the time of induction have been studied A lag phase of 35 degrees C, followed by exponential and stationary phases of 42 and 28 degrees C respectively, allowed an increase of about 27% of UGT2B4 per litre of culture compared to the typical 28-42 degrees C late induced batch culture.