Page W J
Can J Microbiol. 1978 Mar;24(3):209-14. doi: 10.1139/m78-038.
The phenotypes of Azotobacter vinelandii ATCC 12837 strains defective in nitrogen fixation (Nif-) were characterized by intrageneric transformation with known Nif- strains of A. vinelandii OP. These former mutant strains were used as recipients for intergeneric transformation by deoxyribonucleic acid (DNA) prepared from Rhizobium spp. to determine if the rhizobia would transform the Azotobacter Nif- phenotypes to Nif+. The frequency of Nif+ transformants using Rhizobium DNA was always less than the frequency using Azotobacter wild-type DNA but was greater than the spontaneous reversion frequency. The Azotobacter Nif+ recombinants also were stable. DNA from all of the Rhizobium spp. transformed to Nif+ Azotobacter mutants defective in the nitrogenase component I (molybdoferredoxin); however, some recombinants had a lower nitrogenase activity and a delayed nitrogenase depression time. Mutants defective in the pleiotrophic transcriptional control of both nitrogenase components were transformed to Nif+ by the asymbiotic nitrogen fixing Rhizobium sp. 32H1 and 41A1, but not the symbiotic nitrogen-fixing species. The significance of these results and the possible future applications of this system are discussed.
通过用已知的棕色固氮菌OP的固氮缺陷型（Nif-）菌株进行属内转化，对棕色固氮菌ATCC 12837固氮缺陷型菌株的表型进行了表征。这些先前的突变菌株被用作受体，通过从根瘤菌属制备的脱氧核糖核酸（DNA）进行属间转化，以确定根瘤菌是否会将棕色固氮菌的Nif-表型转化为Nif+。使用根瘤菌DNA获得Nif+转化体的频率总是低于使用棕色固氮菌野生型DNA的频率，但高于自发回复频率。棕色固氮菌的Nif+重组体也很稳定。所有根瘤菌属的DNA都能将固氮酶组分I（钼铁蛋白）缺陷的棕色固氮菌Nif-突变体转化为Nif+；然而，一些重组体的固氮酶活性较低，固氮酶抑制时间延迟。固氮酶两个组分的多效转录控制缺陷的突变体被非共生固氮根瘤菌32H1和41A1转化为Nif+，但共生固氮物种不能。讨论了这些结果的意义以及该系统未来可能的应用。
