Microbial Ecology

Barophiles (piezophiles or barophilic bacteria) are bacteria which grow preferentially or exclusively at moderately high hydrostatic pressures.
Examples: Photobacterium profundum, Schewenella benthica, Colwellia psychrerythraea

Halophiles are organisms that live in high salt concentrations.
Dunaliella and Nitzschia: Both are eukaryotic halophiles.
Dunaliella is a type of halophile green micro-algae.
Nitzschia is a common halophile diatom.

Psychrophiles would be expected to grow at refrigeration temperatures.
Psychrophiles grow at 0°C and has an optimum growth temperature of 15°C or lower.

Methanopyrus is a rod-shaped hyperthermophilic methanogen, discovered on the wall of a black smoker from the Gulf of California at a depth of 2000 m, at temperatures of 84–110 °C.
Pyrodictium is a genus of submarine hyperthermophilic archaea whose optimal growth temperature ranges is 80 to 105 °C.

Alicyclobacillus, Ferroplasma, Picrophilus, and Sulfolobus: All are acidophiles (optimum growth between pH 0 and 5.5).

Aerotolerant anaerobe grow equally well in presence or absence of oxygen.

Campylobacter is a genus of bacteria that are Gram-negative, spiral, and microaerophilic. Microaerophiles require oxygen levels in the range of 2 to 10% for their growth and are damaged by the normal atmospheric level of oxygen (20%).

Desulfotomaculum carboxydivorans is a moderately thermophilic, anaerobic, chemolithoheterotrophic, sulfate-reducing bacterium.

A biofilm is any group of microorganisms in which cells stick to each other adhering on a surface.

Chlamydomonas nivalis is psychrophile (grows at 0°C and has an optimum growth temperature of 15°C or lower).
Listeria monocytogenes is psychrotroph (can grow at 0–7°C; has an optimum between 20 and 30°C and a maximum around 35°C).
Escherichia coli is mesophile (has growth optimum around 20–45°C).
Cyanidium caldarium is thermophile (can grow at 55°C or higher; optimum often between 55 and 65°C).

Secondary treatment systems are classified as:
Fixed-film or attached growth systems: It includes trickling filters, biotowers, and rotating biological contactors, where the biomass grows on media and the sewage passes over its surface.
Suspended-growth systems: It include activated sludge, where the biomass is mixed with the sewage and can be operated in a smaller space than trickling filters that treat the same amount of water.

Peptostreptococcus, Propionibacterium, Treponema, Veillonella: All are obligate anaerobes.

Primary treatment usually includes the removal of large solids from the waste water via physical settling or filtration.
Secondary treatment typically removes the smaller solids and particles remaining in the waste water through fine filtration aided by the use of membranes or substantially degrade the biological content of the sewage which is derived from human waste, food waste, soaps and detergent through the use of microbes.
Tertiary treatment involves the disinfection of the wastewater through chemical or energetic means.

Both assertion as well as reason statements is correct and R is correct explanation of A.
Halophiles are salt-loving organisms that flourish in hypersaline environments and can be classified as slightly, moderately or extremely halophilic, depending on their requirement for salt concentration. They include both prokaryotic as well as eukaryotic microbes with the capacity to balance the osmotic pressure of the environment and resist the denaturing effects of salts.

Soil Microbiology is the study of soil inhabiting microborganisms, their functions and effects soil properties.
The microbial ecosystem of soil includes biotic and abiotic components of soil.