Question

Select the option that includes a pair of biofertilisers

• A. Azotobacter and BGA
• B. Nostoc and E.coli
• C. Rhizobium and Salmonella
• D. Salmonella typhi and E.coli

Answer 1

The correct option is A Azotobacter and BGA

Biofertilizers are organisms that enrich the nutrient quality of the soil and promote plant growth by increasing the supply or availability of essential nutrients.

The main sources of biofertilizers are bacteria, fungi and cyanobacteria (BGA).

Bacteria:

• Rhizobium is a symbiotic nitrogen fixing bacterium. It is found in symbiotic association with the root nodules of plants belonging to the legume family.
• Azotobacter is a free-living nitrogen fixing bacterium. They live freely in the soil and perform nitrogen fixation.

BGA (Blue-green algae) or cyanobacteria

• Nostoc is an autotrophic cyanobacteria which can fix atmospheric nitrogen. Blue green algae also add organic matter to the soil and increase its fertility.

Salmonella typhi is a pathogenic bacterium that causes typhoid fever in human beings.

E. coli are bacteria that live in the intestine of humans and these are mostly harmless.

Hence, option a is the correct answer.