Extremophiles Quiz

Extremophiles

• Microorganisms that survive in highly fluctuating physical conditions like temperature, pH, pressure, nutrient availability, radiation, salinity, etc.
• They not only tolerate extreme conditions but require these environments for their survival and growth.

Types of Extremophiles

• Hyperthermophiles: Withstand temperatures above 80°C, mainly from Archaea domain, found in deep sea hydrothermal vents, hot springs, and Yellowstone National Park.
• Thermophiles: Optimum temperature for survival and growth is around 60–80°C, represented by a higher number of species including enterobacteria, photosynthetic bacteria, and Archaea bacteria.
• Mesophiles: Optimum temperature for survival and growth is around 15–40°C.
• Psychrophiles: Survive and grow optimally at very low temperatures ranging from -20°C to 20°C, found in permanently cold places like polar regions and deep oceans.
• Acidophiles: Survive in extremely acidic environments.
• Alkalophiles: Survive in extremely alkaline environments.
• Halophiles: Survive in extremely salty environments.
• Radiophiles: Survive in environments with high levels of radiation.
• Capnophiles: Survive in environments with high CO2 levels.
• Oligotrophes: Survive in environments with low nutrient levels.
• Xerophiles: Survive in extremely dry environments.
• Barophiles: Survive in environments with high pressure.

Adaptation Strategies

Hyperthermophiles

• Molecular adaptation: High GC content to stabilize intramolecules and RNA modifications in nucleoside sequence.
• Horizontal gene transfer (HGT) for DNA repair.
• Proteins: Less frequent amino acids, involved in imposing thermal stability in the form of heat shock proteins.
• Membrane: Lipid branched hydrocarbon chains bonded by ether linkage with glycerol phosphate to maintain rigidity.

Thermophiles

• Molecular: High concentration of binding proteins with positively charged DNA and high GC content provides resistance towards DNA denaturation.
• Cell membrane: Structural changes in membrane lipids, such as acylation, branching, saturation, and unique hydrocarbon chains.
• Protein: High molecular weight heat shock proteins (HSP) are observed.

Psychrophiles

• Protein: Higher content of α-helix relative to β-sheet to maintain flexibility under low temperature.
• Anti-freezing proteins are produced.
• Membrane: Modified by an increased ratio of saturated to polyunsaturated fatty acid to maintain membrane fluidity.
• Genes responsible for cell membrane biogenesis are over-expressed.

Biotechnological Applications

• Thermophiles and their products are used in industry due to their catalytic activity and thermodynamic reactions at high temperatures.
• Applications include production of Taq DNA polymerase, amylase enzyme, protease enzyme, and chitinase.