Study On The Expression Of Vitreoscilla Hemoglobin Gene In The Bacillus Pumilus

Co-Expression of Vitreoscilla hemoglobin gene (vgb) could enhance production of proteins in several bacterial growth under the low level oxygen.In our research, two recomainant plasmids were constructed by inserting the mature peptide-coding sequence of the Vitreoscilla hemoglobin gene downstream of the Bacillus subtilis promoter P43 and Bacillus pumilus alkaline protease promoter wBp to the shuttle vector respectively, and called pSUP43vgb and pSUwBpvgb. To study the effect of Vhb on cell growth, these expression plasids were transformed into B.pumilus UN-31-C-11,B.subtilis WB600 and Escherichia coliBL21. SDS-PAGE and carbon monoxide binding assay demonstrated that VHb was expressed in all three species. It was also found that recombinant plasmids could improve cell growth in three host strains; especially enhance the production of the Alkaline Protease and protein secretesecrete in UN-31-C-11 .Under normal O₂ or low O₂ condition, these transformants showed different optical density comparing with the control. In B.pumilus, cells coming from recombinant expression plasmids had 20% cell density higher than the control in the late exponential phase.Meanwhile.recombinant plasmids could increase the alkaline protease production 30% higher than the control.The results also displayed that P43 promoter had effect higher than wBp in promoting the expression of fused vgb gene.