Microbiology and Nitrogen Cycle

Nitrogen fixation is the process of converting atmospheric nitrogen (N2) into organic compounds, such as amino acids, which can be used by living organisms. While NH3 is an intermediate product, the biological goal is the synthesis of amino acids.

Azotobacter is a genus of free-living, non-legume nitrogen-fixing bacteria. Rhizobium is associated with legumes.

Rhizobium helps in nitrogen fixation.

They use sunlight as an energy source and convert into biomolecules.

E.coli lives in the small intestine of humans

Biogas is pathogen free because anaerobic digestion inactivates pathogens and parasites and is quite effective in reducing the incidence of water borne diseases.

 Nodules with nitrogen fixing bacteria are present in the roots of gram.Their ability to fix gaseous nitrogen makes legumes an ideal agricultural organism as their requirement for nitrogen fertilizer is reduced.

 Pea plant can fix nitrogen from air.Nitrogen fixation is a process in which nitrogen (N2) in the atmosphere is converted into ammonium (NH4+) or nitrogen dioxide (NO2).

 The process of conversion of ammonia to nitrite by microbes is called nitrification.The transformation of ammonia to nitrite is usually the rate limiting step of nitrification. Nitrification is an important step in the nitrogen cycle in soil.

 The enzyme nitrogenase is  required for nitrogen fixation.All nitrogenases have an iron- and sulfur-containing cofactor that includes a heterometal complex in the active site (e.g., FeMoCo). 

 Rhizobium is a nitrogen fixing bacterium.they are Gram-negative, motile, non-sporulating rods.

Among the given options, cyanobacteria belong to blue-green algae.Cyanobacteria is a phylum of bacteria that obtain their energy through photosynthesis.

Blue-green algae fixes atmospheric nitrogen.

Bacillus bacteria has flagella.

Gram positive bacteria retains the purple colour of the crystal violet stain. This retention is facilitated by the thick peptidoglycan layer in their cell wall.