常压室温等离子体诱变选育高固氮酶活褐球固氮菌

为增强固氮酶活性以提高现有固氮菌的固氮能力，采用常压室温等离子体(atmospheric and room temperature plasma，ARTP)诱变技术处理褐球固氮菌（Azotobacter chroococcum）CICC21686，用乙炔还原法筛选具有高固氮酶活性的突变株28s-20，并观察该突变株酶活的遗传稳定性；通过梯度温度和pH培养，探究高酶活突变株的生物学活性；采用盆栽试验，探究突变株对玉米植株干重及全氮量的影响。结果表明，复筛获得突变株28s-20的固氮酶活较出发菌株提高了101.72%；经5次传代，证实该菌株具有良好的遗传稳定性；突变株最适生长温度为28 ℃，培养基初始pH为7.5；与野生株相比，突变株显著增加玉米干重及全氮量，分别提高21.16%和34.36%。诱变高酶活菌株为褐球固氮菌的菌种优化及农业生物固氮提供了技术支持。

Mutation Breeding of Azotobacter chroococcum with High Nitrogenase Activity by Atmospheric and Room Temperature Plasma

In order to enhance the nitrogenase activity of bacteria so as to improve the nitrogen-fixing ability of nitrogen-fixing bacteria, Azotobacter chromococcus CICC21686 was treated by atmospheric and room temperature plasma (ARTP) mutagenesis technology. The mutant strain 28s-20 with high nitrogenase activity was screened by acetylene reduction method, and the genetic stability of the enzyme activity of the mutant was observed. The optimum growth temperature and initial pH of medium for mutant strain were determined by setting gradient temperature and pH cultivation. Pot experiment was conducted to investigate the effect of mutant strain on dry weight and total nitrogen content of maize plants. The results showed that after two rounds of screening, the nitrogenase activity of the mutant strain 28s-20 was increased by 101.72% compared with that of the original strain. After 5 generations cultivation, it was demonstrated that its nitrogenase activity had good genetic stability. The optimum growth temperature of the mutant was 28 ℃, and the initial pH of culture medium was 7.5. Compared with the wild strain, the mutant strain significantly increased the dry weight and total nitrogen content of maize by 21.16% and 34.36%, respectively. The mutant strain with high nitrogenase activity provided technical support for strain optimization of A. chroococcum and agricultural biological nitrogen fixation.