质子自杀法选育克雷伯氏菌产乳酸突变株

Isolation and Characterization of Klebsiella oxytoca M5al Mutants with Proton Suicide Method

摘要:

以产酸克雷伯氏菌(Klebsiella oxytoca) M5al为出发菌株, 经亚硝基胍诱变处理, 运用质子自杀法选育, 从含0.17 mol/L NaBr-NaBrO3的初筛平板上选出44个具有稳定遗传性的单菌落, 然后结合培养基优化后的摇瓶发酵复筛, 获得3个产乳酸突变株, 其乳酸脱氢酶活性分别为出发菌株的50.6%、58.8%、61.3%。对其中乳酸脱氢酶活性最低的菌株在5 L自动发酵罐上进行批式发酵, 结果显示: 突变株乳酸产量大幅降低, 而乙酸、1,3-丙二醇的产量则显著增加。

关键词:质子自杀, 产酸克雷伯氏菌, 产乳酸突变株, 乳酸脱氢酶

Abstract:

Klebsiella oxytoca M5al was used as the original strain to breed mutants after mutagenesis with NTG, 44 single colony were obtained from medium containing 0.17 mol/L NaBr-NaBrO3 (proton suicide method) and 3 lactic acid-producing mutants were selected by shaking cultivation in optimized medium, their lactate dehydrogenase activity was only 50.6%、58.8%、61.3% of the parent strain, respectively. The lowest one of them batch-cultured in 5 L fermenter, results indicated that the yield of lactic acid of the mutant was decreased remarkably, reversely, acetic acid and 1,3-propanediol were increased observably.

Key words:Proton suicide, Klebsiella oxytoca, Lactic acid-producing mutant, Lactate dehydrogenase