Multiple choice Which of the following bacteria is a free-living N2 fixer ? Anaplasma Actinomyces israelii Agrobacterium tumefaciens Azotobacter vinelandii Reveal answer Fill a bubble to check yourself D Correct answer Explanation Azotobacter vinelandii is a free-living N2 fixer which is capable of producing numerous phytohormones and vitamins in the soil. It is diazotroph. It is used to study nitrogen fixation.