Which of the following pair represents free living nitrogen fixing aerobic bacteria?
- Pseudomonas and Thiobacillus
- Rhizobium and Frankia
- Azotobacter and Beijernickia
- Anabaena and Rhodospirillum
Answer
(3) Azotobacter and Beijernickia
Solution
As per NCERT, examples of free-living nitrogen-fixing aerobic microbes are Azotobacter and Beijernickia, while Rhodospirillum is anaerobic and free-living.
⇒ Rhizobium and Frankia are symbiotic nitrogen fixers.
⇒ Pseudomonas and Thiobacillus are denitrifying bacteria.
⇒ Anabaena is a cyanobacterium; Rhodospirillum is anaerobic.
Answer: (3)