Microbiology and Nitrogen Cycle

This is the correct option, as Rhizobium is a bacteria.

This is the correct option. Rhizobium present in the root nodules of leguminous plants fix atmospheric nitrogen and increases the fertility of the soil.

Yes, it is the correct answer. Pyrodictium is a genus of submarine hyperthermophilic archaea whose optimal growth temperature ranges is 80 to 105°C.

Yes, it is correct. Voges–Proskauer test is used to detect acetoin in bacterial broth culture. The test is performed by adding alpha-naphthol and potassium hydroxide to the Voges-Proskauer broth, which has been inoculated with bacteria. A cherry red colour indicates a positive result, while a yellow-brown colour indicates a negative result. Both Escherichia coli and Proteus mirabilis give negative Voges–Proskauer test.

Yes, it is the correct answer. Rhizobium is a nitrogen-fixing bacteria living in a symbiotic relationship with legumes.

Yes, it is the correct answer. Barophiles (barophilic bacteria) are bacteria which grow preferentially or exclusively at moderately high hydrostatic pressures. Examples: Photobacterium profundum and Colwellia psychrerythraea

The partially digested organic material left in soil, called humus. Bacterial action changes dead leaves into humus. 

Correct sequence is Nitrogen fixation, nitrogen assimilation, ammonification, nitrification, denitrification.

They are called psychrophiles.

The word 'bacillus' is of Latin origin, and its plural form follows the rule of changing the '-us' suffix to '-i'.

V. shiloi is infectious only during warm periods. Elevated temperature increases the virulence of V. shiloi, which then become able to adhere to a beta-galactoside-containing receptor in the surface mucus of the host coral.

Nitrogen is a gas that cannot be directly used by plants. Rhizobium is bacteria present in root nodules of leguminous plants that converts the atmospheric nitrogen into nitrogen salts to be used in soluble form.

 Symbiotic relationship is the relationship between two groups of organisms both of which are benefited from each other in a mutual manner. Rhizobium is the bacterium, which lives in root nodules of leguminous plants. It gets its shelter from the plant and in reverse it fixes the atmospheric nitrogen to make it available to the plant. 

 Putrefying bacteria is the bacterial form, which converts organic form of nitrogen into ammonia. This process is known as ammonification. Nitrobacterium converts nitrites into nitrates. Nitrosomonas converts nitrogen into nitrites and Rhizobium fixes atmospheric nitrogen. 

 Nitrobacterium is the bacterial form, which converts the already formed nitrites into more soluble andmore easily absorbable nitrogen salts i.e. the nitrates.