Question

All of the following statements concerning the actinomycetes filamentous soil bacterium, Frankia are correct except that Frankia

• A. Can induce root nodules on many plant species
• B. Cannot fix nitrogen in the free-living state
• C. Like Rhizobium, it usually infects its host plant through root hair deformation and stimulates cell proliferation in the host's cortex
• D. Forms specialized vesicles in which the nitrogenase is protected from oxygen by a chemical barrier involving triterpene hopanoids

Answer 1

Answer: (B)

Cannot fix nitrogen in the free-living state

Frankia, aerobic Gram-positive actinomycetes can induce root nodules in about 8 families. These bacteria cannot fix nitrogen in free living state. They can infect the host root by intracellularly by infecting curled root hair or intercellularly by penetrating between two rhizoderm cells and then progress toward cortical cells. These bacteria in free-living state form diazovesicles containing nitrogenase which is protected from oxygen by a series of laminated lipid layers.

So all the statements are correct.