Production of Vitamin B6 in Rhizobium

The production of vitamin B6 was studied in about 1,590 bacterial isolates from soil, and an isolate, 28-21, identified as Rhizobium leguminosarum was obtained as a vitamin B6 high producer. Then, the production of vitamin B6 by commercially available Rhizobium strains was examined, and many of the tested strains excreted large amounts of vitamin B6 into the culture broth. The best producer of vitamin B6 was R. meliloti IFO 14782, which produced 51 mg per liter. Media study for the vitamin B6 production was done with R. meliloti IFO 14782; the strain was able to excrete 84 mg of vitamin B6 per liter, 79 mg per liter of which was pyridoxol.