Microbiology and Nitrogen Cycle

Nitrogen fixation is the natural process, in which the atmospheric nitrogen (N₂) is converted into ammonia. Rhizobium is a soil bacteria which has the capacity to fix atmospheric nitrogen.

These bacteria can produce organic compounds from inorganic raw materials by using energy generated from the oxidation of inorganic substances.

Streptomyces olivaceus are Gram positive bacteria with high GC content and are characterised by a complex secondary metabolism. They produce over two-thirds of the clinically useful antibiotics of natural origin. Cyanocobalamin is synthesised by utilising Streptomyces olivaceus.

These bacteria are found in the alimentary canal of human beings. They keep a check on the growth of harmful putrefying bacteria in the gut of the human beings. They also release vitamins K and B₁₂ which are necessary for blood components. In return human host provides shelter and food for these bacteria. So, they are symbiotic bacteria.

It is an anaerobic, motile, gram-positive bacterium. It plays significant role in the fermentation process for second generation biofuels.

It is a facultatively aerobic, Gram +ve coccus-shaped bacteria. It is commonly found in the human oral cavity. It causes tooth decay in humans.

Veillonella is anaerobic gram negative cocci.

These are the ancient bacteria that can produce methane gas used in biogas plants.

Yes, it is the correct answer as the microbes reside in the root nodules of leguminous plants. They can fix nitrogen from the air into soil and increase the soil fertility.

Air helps in the growth of aerobic bacteria in the clarified water.

Anaerobic bacteria is the connecting link between sludge and biogas production.

This is the correct option. The root nodules of millet do not have nitrogen-fixing bacteria called rhizobium bacteria. It is a non-leguminous plant.

Lactobacillus grows luxuriantly in broth having pH 5.35. This pH is optimum for the growth of Lactobacillus.

Pantoea agglomerans grows luxuriantly in Pikovskaya medium and creates a clear zone indicating phosphate solubilisation.

Venkataraman Ramakrishna (VR) medium is a transport medium for the transportation of feces from suspected cholera patients.  These samples contain vibrio cholerae.