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Tea, fir, poplar for the study, to explore the woody plants in the rhizosphere of nitrogen fixation system. Camellia select three typical plots, numbered as follows: A1, A2, A3; fir select four typical plots, numbered as B1, B2, B3, B4; poplar forest which is selected, numbered y Y. A comparative analysis of tea, fir rhizosphere soil microbial ecological distribution, rhizosphere soil enzymes (catalase, invertase, urease, protease, cellulase) activity in rhizosphere soil pH value, the results show that: tea, fir rhizosphere distribution of microbial ecology, ecological distribution of the root rhizosphere soil activity and rhizosphere soil pH value and the nitrogen-fixing bacteria is not a positive correlation. Specific reasons and relations have not been studied. Improved Do's medium from the three rhizosphere, the root surface, root separation to the United nitrogen-fixing bacteria, the enzyme activity was determined by acetylene reduction method, has acetylene reduction activity. Camellia oleifera rhizosphere isolated nitrogenase activity greater than 1nmolC 2 H 4 / the strains h.ml 8, of which the most active strains aa33 enzyme activity of 2.76nmolC < sub> 2 H 4 / h.ml; fir rhizosphere separated into six activity greater than 1nmolC 2 H 4 / nitrogen-fixing bacteria h.ml; most active strains ba41 the enzyme activity 2.49nmolC H 4 / h.ml; the same Poplar rhizosphere nitrogen-fixing bacteria isolated from 12 strains with high enzyme activity is Y12, the Y22, activity, 2.98,2.76 nmolC 2 H 4 / h.ml. Strains aa33 ba41, Y12, and Y22 in different media, different carbon sources, different temperatures, different pH conditions under nitrogen-fixing characteristics were studied. Select one of four different formulations of the medium: improvement Do's medium, sodium gluconate medium Ashby no nitrogen medium and root cooking liquid medium; 7 different carbon sources, glucose sucrose mixed sodium malate carbon source, glucose, sucrose, sodium malate, maltose, mannose, starch; setting different temperatures: 20 ° C, 25 ° C, 30 ° C, 35 ° C, 40 ° C, 45 ° C; different pH: 5.0,5.5,6.0 6.5,7.0,7.5,8.0,9.0 The result is: (1) in the different media conditions: 4 nitrogenase activity of the bacteria. Activity on the Do's medium high compared to several other medium; (2) under the conditions of different carbon sources: four strains of sucrose use, followed by sodium malate, on the other carbon sources The different strains preferences; (3) under different temperature conditions: aa33 and the y12 optimal nitrogen fixation temperature to 35 ° C, ba41 and Y22 optimum nitrogen fixation temperature of 30 ° C to 35 ° C, 4 kinds of bacteria nitrogen fixation temperature of 20 ° C - between 40 ° C, a wide range of temperature adaptation; (4) under different pH conditions: Y12 nitrogen fixation optimum pH around 6.0, and the other three nitrogen fixation optimum pH between 6.0 and 7.0, four nitrogen-fixing bacteria acidic limit of about 5.0, the alkaline limit of about 9.0 to adapt to a wide range of pH. Made the observation of morphological and cultural characteristics of the four bacteria, and the strain Y12 and Y22 made further physiological and biochemical identification. Cultural characteristics and physiological and biochemical characteristics, initially identified based on the morphological characteristics of Y12 and Y22, y12 Flavobacterium (Flavobacterium), Y22 Alcaligenes (Alcaligenes).
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