Question

1.     What is an extremophile? List at least three different types (not species) of extremophiles and the type of environment where they would be found.

2.     Identify two bacterial species that have a significant impact (one positive or beneficial, and one negative or pathogenic) on human life. Explain how these organisms affect humans.

Answer 1

Ans. #1. The organisms that exhibits optimum growth in physically and/or chemically extreme conditions are called extremophiles. Most of them belong to the kingdom Archaebacteria.

Three types of extremophiles are as follow-

#I. Thermophiles: The organisms that exhibit optimum growth temperature at or above 70.0⁰C. Example- Thermus aquaticus (an Archaea)

#II. Halophiles: The group of organisms that exhibit optimum growth in high salt concentration (0.20 M NaCl or above). Example- Dunaliella salina (an algae)

#III. Acidophiles: The group of organisms that exhibit optimum growth in low pH (pH 3 or below). Example- Heliobactor pylori (a bacteria)

#2. Two bacterial species with significant impact on human life:

#I. Harmful species: Heliobactor pylori causes peptic ulcer disease in humans.

#II. Beneficial species: Paracoccus denitrificans is used to produced vitamin B12 at inductrial scale.