Biosynthesis of poly⁃γ⁃glutamic acid is an aerobic process. Therefore we tried to transform the strain by genetic engineering to improve its ability of using oxygen. First,the recombinant plasmid pMA5⁃P43⁃vgb was constructed with the overlapping PCR method connecting Bacillus subtilis P43 promoter to Vitreoscilla hemoglobin gene vgb, then transformed into Bacillus subtilis NX⁃2, to obtain a recombinant strain B.subtilis NX⁃2(vgb+).The molecular size of hemoglobin VHb in recombinant strain B. subtilis NX⁃2( vgb+) was 1�6 × 104 by SDS⁃PAGE. Further, the carbon monoxide difference spectra verified that the target protein had a physiological activity in B. subtilis NX⁃2 ( vgb+) . The experiments in the 7�5⁃L fermentor showed that the recombinant strain increased the biomass 41�2% and the γ⁃PGA production 7�5% than the original strain. The research lay a foundation for the γ⁃PGA industrial production.%γ聚谷氨酸（γ PGA）的微生物合成是高消耗氧的生物过程，采取基因工程手段改造γ PGA生产菌株Bacillus subtilis NX 2，以提高细胞利用氧的能力。利用重叠 PCR 方法将 P43强启动子与透明颤菌血红蛋白（ VHb）基因vgb拼接，插入大肠杆菌枯草芽胞杆菌穿梭质粒pMA5上，得到重组质粒pMA5 P43 vgb，并将其转化至B． subtilis NX 2中，从而获得重组菌B．subtilis NX 2（ vgb＋）。经SDS PAGE分析和CO差光谱法证明VHb能在γ PGA生产菌株中成功表达，且具有生理活性，大小约为1�6×104。在7�5 L发酵罐上对重组菌B． subtilis NX 2（ vgb＋）进行发酵性能考察，结果显示：重组菌比出发菌的生物量提高了41�2％，γ PGA 的产量提高了7�5％，传代多次表明重组菌具有良好的发酵稳定性。该研究为γ PGA的进一步工业化生产奠定了基础。
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