[Infectiology] Archaea

Taxonomy 

• Archaea 

Archaea is a domain and kingdom of microscopic organisms. Archaea are prokaryotes.   

 

Classification  

Domain : Prokaryota, Archaea  
Kingdom : Archaea  

 

What are archaea?

Originally it was believed that archaea were a subtype of bacteria, but this was proven to be untrue and the three domain system arose.

Most of the known archaea are similar to bacteria in shape and size (morphology). However, some archaea have a morphology, which has never been seen in any known bacteria.
Archaea and bacteria have many differences in ancient systems. For example, all bacteria have a nearly identical set of essential enzymes, which are involved in transcription and translation. All archaea have their own set of equivalent enzymes. The archaeal enzymes are different to the bacterial enzymes. These enzymes are fundemental to life, so they must be very ancient, and any differences between them must have developed long ago.

There are unique technical challenges to detecting archaea. Even today, archaea are relatively difficult to identify. The isolation of DNA from a particular species of archaea would require specific protocols.

 

Many bacterial diseases have been well described. What are the known archaeal diseases?

Several species of archaea have been proven to live in the human body as commensals and mutualists, for example, methogenic species living in the human intestines. Archaea certainly have the capability to live parasitic lives, like so many bacteria. Several experiments have shown that injections of archaea into organs of model organisms can cause tissue damage and death.

However, to date, there is no convincing evidence of a disease caused by archaea. It's possible that some feature of potentially pathogenic archaea makes them incapable of surviving inside the mammalian body. It is more likely because of the difficulty in detecting and identifying them. As technology advances, the relationship between archaeal colonisation and human diseases should become more clear.