关键词: 常压室温等离子体, 褐球固氮菌, 固氮酶, 乙炔还原法

Abstract: 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.

Key words: atmospheric pressure room temperature plasma (ARTP), Azotobacter chroococcum, nitrogenase, acetylene reduction assay