Explanation

Nitrogen-fixing bacteria, microorganisms capable of transforming atomospheric nitrogen into fixed nitrogen, inorganic compounds usable by plants. Two kinds of nitrogen fixers are recognized (i) Free-living (non-symbiotic) bacteria, including the cyanobacteria (blue-green algae) Anabaena and Nostoc and such genera as Azotobacter, Azospirillum and Clostridium (ii) Mutualistic (symbiotic) bacteria such as Rhizobium, associated with leguminous plants, and Spirillum lipoferum, associated with cereal grasses Pseudomonas is a common bacterium that can cause disease in animals, including humans