Which one of the following microbes is not the cyanobacteria?

The correct answer is Option (2) → Glomus

Cyanobacteria (blue-green algae) are autotrophic microbes found in water and on land. Many of them fix atmospheric nitrogen, so they are used as biofertilisers, especially in paddy fields.

(1) Oscillatoria — A cyanobacterium.

(2) Glomus — Not a cyanobacterium. It is a fungus that forms mycorrhiza with plant roots. The fungus takes in phosphorus from the soil and passes it to the plant.

(3) Anabaena — A cyanobacterium.

(4) Nostoc — A cyanobacterium.

Note: A similar question was also asked in CUET (UG) 2023 on 26-05-2023 (Slot 3).

NCERT Extract:
Microbes as Biofertilisers – “… Fungi are also known to form symbiotic associations with plants (mycorrhiza). Many members of the genus Glomus form mycorrhiza. The fungal symbiont in these associations absorbs phosphorus from soil and passes it to the plant. Plants having such associations show other benefits also, such as resistance to root-borne pathogens, tolerance to salinity and drought, and an overall increase in plant growth and development. … Cyanobacteria are autotrophic microbes widely distributed in aquatic and terrestrial environments many of which can fix atmospheric nitrogen, e.g. Anabaena, Nostoc, Oscillatoria, etc.”