Bradyrhizobium elkanii is a species of legume-root nodulating

Root nodule

Root nodules occur on the roots of plants that associate with symbiotic nitrogen-fixing bacteria. Under nitrogen-limiting conditions, capable plants form a symbiotic relationship with a host-specific strain of bacteria known as rhizobia...

, microsymbiotic

Symbiosis

Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...

 nitrogen-fixing

Nitrogen fixation

Nitrogen fixation is the natural process, either biological or abiotic, by which nitrogen in the atmosphere is converted into ammonia . This process is essential for life because fixed nitrogen is required to biosynthesize the basic building blocks of life, e.g., nucleotides for DNA and RNA and...

 bacterium originally identified as DNA homology group II strains of B. japonicum

Bradyrhizobium japonicum

Bradyrhizobium japonicum is a species of legume-root nodulating, microsymbiotic nitrogen-fixing bacterium species. B. japonicum is identified as a DNA homology group .B...

 . In 1988, it was discovered that only DNA homology group II strains caused a destructive bleaching of leaves, termed scientifically "microsymbiont-induced foliar chlorosis", which was widespread in soybean

Soybean

The soybean or soya bean is a species of legume native to East Asia, widely grown for its edible bean which has numerous uses...

 production fields of the southern United States

Southern United States

The Southern United States—commonly referred to as the American South, Dixie, or simply the South—constitutes a large distinctive area in the southeastern and south-central United States...

 . Whole cell fatty acid content together with antibiotic resistance profiles were major phenotypic differences that helped establish DNA homology group II strains as a new species, Bradyrhizobium elkanii .