Q. Which of the following bacteria fixes nitrogen without any plant association?
A) $Rhizobium$
B) $Nostoc$
C) $Anabaena$
D) $Azotobacter$
Explanation
$Azotobacter$and$\ Beijerinickia$ are aerobic free living, saprotrophic (heterotrophic), nitrogen fixing bacteria. $Azotobacter$sp (aerobic) are the main nitrogen fixing free living bacteria.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.