These are not used as biofertilizers when present as free living organisms.A. RhizobiumB. GlomusC. AzospirillumD. Azotobacter

Rhizobium can not be nitrogen fixer when occurs freely in the soil. It fixes nitrogen only when associated with roots of legumes. Glomus does not act as biofertilizer when occurs freely in the soil. It behaves as biofertilizer when associated with the roots of higher plants.