11.) You have studied extremophiles as part of your Biology. What are they, and can you give one example of such extremophiles and mention their usage in research.

11.) You have studied extremophiles as part of your Biology. What are they, and can you give one example of such extremophiles and mention their usage in research.

A.) 

Extremophile Definition

Extremophiles are organisms that have evolved to survive in environments once thought to be entirely uninhabitable. These environments are inhospitable, reaching extreme conditions of heat, acidity, pressure, and cold that would be fatal to most other life forms. Because extremophiles live on extreme ends of the spectrum, they can indicate the range of conditions under which life is possible.

One important thing to note, however, is that extremophiles are “extreme” only from an anthropocentric perspective. For example, while oxygen is indispensible to ourselves and much of life on Earth, many organisms flourish in environments without oxygen at all.

Extremophiles can be divided into two broad categories: extremophilic organisms, and extremotolerant organisms. As the suffix “philic,” translated to “loving,” suggests, extremophilic organisms require one or more extreme conditions in order to thrive, while extremotolerant organisms grow optimally at more ‘normal’ conditions but are still able to survive one or more extreme physiochemical values.

Most extremophiles are microscopic organisms belonging to a domain of life known as archaea. However, to say extremophiles are restricted to this domain would be incorrect. Some extremophiles belong in the bacteria domain, and some are even multicellular eukaryotes!

Types of Extremophiles

Of course, different environmental conditions require different adaptations by the organisms that live those conditions. Extremophiles are classified according to the conditions under which they grow. Usually, however, environments are a mix of different physiochemical conditions, requiring extremophiles to adapt to multiple physiochemical parameters. Extremophiles found in such conditions are termed “polyextremophiles.”

1.) Acidophile   – organisms that live in acidic environments

2.) Alakaliphiles – organisms that live in basic environments, e.g soda lake. 

3.) Psychrophile – organisms that live at temperatures much lower than normal

4.) Xerophile

5.) Barophile (Piezophile)  – organisms that live under high barometric pressure

6.) Halophile – organisms that live in an environment of high salinity

Halophiles are organisms that require high salt concentrations for growth. At salinities exceeding 1.5M, prokaryotic bacteria are predominant. Still, this group belongs to all three domains of life, but in smaller numbers.

Overcoming the challenges of hypersaline environments starts with minimizing cellular water loss. Halophiles do this by accumulating solutes in the cytoplasm via varying mechanisms. Halophilic archaea use a sodium-potassium ion pump to expel sodium and intake potassium. Halotolerant bacteria balance the osmotic pressure by using glycerol as compatible solutes.

Importance in Research

The enzymes secreted by extremophiles, termed “extremozymes,” that allow them to function in such forbidding environments are of great interest to medical and biotechnical researchers. Perhaps they will be the key to creating genetically based medications, or creating technologies that can function under extreme conditions.

Astrobiologists have also taken interest in extremophiles for their remarkable resilience in freezing environments. Extremophiles, or “psychrophiles,” that are active in such environments raise the possibility of life on other planets, as the majority of bodies in the solar system are frozen. Additionally, the biochemical properties of such psychrophiles, such as the ability to use arsenic rather than phosphorus to create energy, furthers the possibility of extraterrestrial life. And, because extremophiles can indicate the range of conditions under which life is possible, they can also provide clues about how and where to look for life on other solar bodies.