Abstract：Abstract Recombinant plasmids pKtac1-act1 and pKtac1-act2 were integrated into Comamonas testosteroni chromosome by electroporation respectively, and two engineering strains were obtained and identified by the analysis of PCR and Southern blot. Expression and stability of 3α-hydroxysteroid dehydrogenase/carbonyl reductase(3α-HSD/CR) of engineering strains were detected. The results indicated that the expression of 3α-HSD/CR almost 20-folds increased in two engineering strains than that of the wild type without inducing; and the expressions of activator and 3α-HSD/CR were quite high and stable when engineering strains inoculated in LB medium with antibiotic; but unstable when inoculated in LB medium without antibiotic. The preliminary results indicate that the expression of 3α-HSD/CR can be regulated by the activator gene.
