Question

All the following statements concerning the Actinomycetes filamentous soil bacterium $Frankia$ are correct except

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

Answer 1

Answer: (E)

All are correct

• Frankia, aerobic Gram-positive actinomycetes can induce root nodules in about 8 families.
• These bacteria cannot fix nitrogen in free living state.
• It causes root hair deformation after it enters the cortical cells and induces the nodule formations, which look like those induced by Rhizobium in legumes.
  
• These bacteria in free-living state form diazovesicles containing nitrogenase which is protected from oxygen by a series of hopanoids lipid layers.
• So all the statements given are correct.

Hence the correct answer is option E.