【摘要】 从小麦、玉米、谷子和甘蔗等作物根表分离获得具有固氮酶活的Azospirillum属细菌58株。根据这些菌在葡萄糖或核糖上不产酸,在蔗糖蛋白胨中不发酵,以及不需要生长素也能生长等特点,将它们定为Azospirillum brasilense种。又根据它们还原硝酸盐、是否累积亚硝酸盐和产生与不产生N₂O的明显差异性,将它们分成两群。从这两群菌在上述作物根表分布的状况看,居于玉米和甘蔗根表的菌株,全部属于第Ⅰ群,谷子根表的全部属于第Ⅱ群、小麦根表的则分属两群。玉米、谷子和甘蔗的根表固氮螺菌具有较强的专一性,而小麦根表固氮螺菌的专一性较弱。更多还原

【Abstract】 Fifty-eight strains of nitrogen fixing bacteria were isolated from rhizoplane of maize wheat, millet and sugar cane. Nitrogenase activities of these bacteria in pure culture were 76.2-1454.4 n mol/bottle/h. These strains of nitrogen fixing bacteria were found to belong to genus Azospirillum based on morphological, physiological and biochemical properties. They were not capable of using glucose as a sole carbon source for growth in nitrogen-free semisolis medium. No acidification of glucose or ribose medium occured. No fermentation ability for peptonsugar was present. Vitamins were not required for growth. They were classified into species Azospirillum brasilense. It contained two groups depending on ability to denitrify nitrite: Group Ⅰ. The strains in this group possesed assimilatory and dissimilatory nitrate and nitrite reductase （nr⁺, nir⁺） produced N₂O. Nitrite was nct accumulated. Group Ⅱ. The strains in this group producing no N₂O only possesed assimilatory and dissimilatory nitrate reductase （nr⁺, nir^- ）. Nitrite was accumuted. The strains found in the roots of maize and sugar cane belonged to group Ⅰ. The strains found in the roots of millet belonged to group Ⅱ. But half of the strains associated with roots of wheat belonged to group. Ⅰ. another half to group Ⅱ. The results in our experiments showed that the bacteria asscciated with roots of maize, millet and sugar cane possesed strong specificity, but the bacteria on the roots of wheat presented poor specificity. Further research on the specificity of Azospirillum is necessary.更多还原