RESUMO
Heme peroxidase EfeB in E. coli belongs to the dye-decolorizing peroxidase (DyP) superfamily. Peroxidases in this superfamily have a good ability in degradation of synthetic dyes, but their physiological functions in organisms are unclear. In order to further understand the physiological function of EfeB, the mutant strain EcoΔefeB was constructed by homologous recombination. The differences between parental strain E. coli BL21 and EcoΔefeB at genome transcription level as well as cell growth under different conditions were compared. The response of efeB to iron ion was also investigated. The results showed that the deletion of efeB gene caused the differential expression of 1 765 genes, which were mainly related to cell metabolic pathway, cell membrane synthesis and flagellum movement. There was no significant difference in cell growth between BL21 and EcoΔefeB at pH 7. 0, but the growth of BL21 was much better than that of EcoΔefeB at pH 4. 5. The functional expression of efeB may support the survival of E. coli at low pH. EfeB was significantly up-regulated when Fe