Quiz

Organisms capable of living in extreme environments:

• Extremophiles are organisms that can live or thrive in extreme environments.

• They can survive conditions such as extreme temperature, radiation, salinity, or pH level.

• Some spores and cocooned bacteria samples have been dormant for more than 40 million years.

• Extremophiles are ecologically dominant in the evolutionary history of the planet.

• They have continued to thrive in the most extreme conditions, making them one of the most abundant lifeforms.

• Studying extreme environments on Earth can help researchers understand the limits of habitability on other worlds.

• Astrobiologists are particularly interested in studying extremophiles to map what is known about the limits of life on Earth to potential extraterrestrial environments.

• Extremophiles can be useful players in the bioremediation of contaminated sites.

• They can also be effective in remediating metals, acid mine drainage, and radioactive materials.

• New sub-types of extremophiles are identified frequently, and the sub-category list for extremophiles is always growing.

• Studying these organisms may help illuminate the mechanisms of both toxicity and deficiency in certain elements.

• The T. brockianus catalase has applications for removal of hydrogen peroxide in industrial processes.DNA Transfer in Extremophiles

• Several biotechnology companies produce DNA modifying enzymes commercially.

• Over 65 prokaryotic species are known to be naturally competent for genetic transformation.

• D. radiodurans is one of the most radioresistant organisms known and is competent to perform genetic transformation.

• Thermus thermophilus and other related Thermus species are also capable of genetic transformation.

• Halobacterium volcanii is capable of natural genetic transformation using cytoplasmic bridges.

• Sulfolobus solfataricus and Sulfolobus acidocaldarius are hyperthermophilic archaea capable of DNA transfer via cellular aggregation and homologous recombination.

• Cellular aggregation in Sulfolobus may enhance species-specific DNA transfer between cells to repair damaged DNA.

• Extracellular membrane vesicles (MVs) might be involved in DNA transfer between different hyperthermophilic archaeal species.

• Plasmids and viral genomes can be transferred via MVs.

• A horizontal plasmid transfer has been documented between hyperthermophilic Thermococcus and Methanocaldococcus species.

• DNA transfer in Sulfolobus may be an early form of sexual interaction.

• The DNA exchange process in Sulfolobus may be crucial under DNA damaging conditions such as high temperatures.