Analysis of the Symbiotic Performance of Bradyrhizobium japonicum USDA 110 and Its Derivative I-110 and Discovery of a New Mannitol-Utilizing, Nitrogen-Fixing USDA 110 Derivative †

摘要: Previously, Bradyrhizobium japonicum USDA 110 was shown to contain colony morphology variants which differed in nitrogen-fixing ability. Mannitol-utilizing derivatives L1-110 and L2-110 have been be devoid of symbiotic nitrogen fixation ability, non-mannitol-utilizing I-110 S-110 efficient at fixation. The objectives this study were determine the effect media carbon sources on N(2)-fixing ability strain compare effectiveness derivative I-110. Based acetylene reduction activity content 41-day-old soybean plants, neither nor cultures grown favoring non-mannitol-using had that statistically superior mannitol-using derivatives. In another experiment 200 individual nodules formed by yeast extract gluconate screened for occupying variant(s) activity. Nodules occupied (large type 0.1% extract-0.05% K(2)HPO(4)-0.08% MgSO(4) . 7H(2)O-0.02% NaCl-0.001% FeCl(3) 6H(2)O [pH 6.7] with 1% mannitol [YEM] plates) a mean equal (small YEM plates). A total 20 large colonial 10 small (I-110-like) isolated purified repeated culture YEG (same as except instead mannitol) media, respectively, followed dilution solutions containing 0.05% Tween 40. After 25 days growth, plants inoculated isolates whole-plant activity, dry weight, contents or better than those either (non-mannitol-using) derivative. Hence, existence mannitol-utilizing fixes obtained from U.S. Department Agriculture, Beltsville, Md., established. This new designated MN-110 because it morphologically indistinguishable non-nitrogen-fixing found earlier Beltsville. DNA-DNA homology restriction enzyme analyses indicated is genetically related other characterized previously.