Nicotinic acid requirement and degradation bySesbania rhizobiumstrain ORS571

Sesbania rhizobium strain ORS571, which grows in the free-living state at the expense of N2 or ammonia, requires nicotinic acid as a growth factor and also uses this vitamin as a nitrogen source in culture medium devoid of ammonia. Consequently, under nitrogen-fixing conditions, Sesbania rhizobium requires about 10-times more nicotinic acid than when grown in the presence of ammonia. The physiological implications of this property are discussed.