| Noun | 1. | family Rhizobiaceae - a small family of rod-shaped bacteria bacteria family - a family of bacteria genus Rhizobium, Rhizobium - the type genus of Rhizobiaceae; usually occur in the root nodules of legumes; can fix atmospheric oxygen Agrobacterium, genus Agrobacterium - small motile bacterial rods that can reduce nitrates and cause galls on plant stems Eubacteriales, order Eubacteriales - one of two usually recognized orders of true bacteria; Gram-positive spherical or rod-shaped forms; some are motile; in some classifications considered an order of Schizomycetes |