Mutant strains of clover rhizobium (Rhizobium trifolii) that form nodules on soybean (Glycine max).

Mutant strains of Rhizobium trifolii that induce nitrogenase activity in the free-living state were isolated. These strains, unlike the wild type, nodulated soybean and mungbean plants, producing effective nodules. One of the strains, strain DT72, also nodulated clover but the nodules were ineffective. Strain DT125 consumed hydrogen gas from the gas phase, which can be coupled to nitrogenase activity under appropriate conditions.