中文摘要：

以Bacillus subtilis GXA-28为出发菌株，采用紫外、微波、氯化锂3种单一诱变及紫外．氯化锂，微波-氯化锂两种复合诱变方式进行诱变育种。经过5轮诱变，13次初筛，8次复筛，总共初筛选3554株，复筛选236株突变菌株。获得1株底物（谷氨酸钠）耐受性为出发菌株的2倍；廿聚谷氨酸产量达24．00g／L左右（比出发菌株高出约33％）的菌株，命名为U-59。经过6代遗传稳定性试验，该菌株性状稳定。

英文摘要：

Bacillus subtilis GXA-28 was used as original γ-PGA-producing strain, which was treated by ultraviolet, microwave, lithium chloride, ultraviolet-lithium chloride and microwave-lithium chloride. After the mutagenesis, thirteen times screening, eight times rescreening, a total of 3554 screening, 236 rescreening, B. subtilis U59 was isolated. It was genetically stable. The substrate tolerance twice as original strain and the γ-PGA yield was attained 24.00g/L, increasing by 33%.