Archaea Versus Eubacteria: Differences Between Archaea and Eubacteria

Eubacteria and archaebacteria (or simply archaea) belong to Kingdom Monera. All members of this kingdom are considered as prokaryotes. There are several differences between eubacteria and archaea which are discussed in this article(Tortora, 2007).

Between eubacteria and archaea, the former is studied more extensively by scientists. Since archaebacteria are usually found in hostile environments such as volcanic vents, it is not practical to study them. Take note that almost all known pathogens on earth are classified under eubacteria (Mukhergee, 2009).

Subclassification

Halobacteria

Halobacteria, an archaea

Archaea are organisms that are usually found in extreme conditions. They are categorized into three phyla: methanogens, halophiles and thermoacidophiles. Methanogens got their name from their ability to convert hydrogen and carbon dioxide into methane.  They are very common in swamps and are responsible for marsh gas. Halophiles, the second group of archaea, derived their name from their ability to survive under extreme salty conditions.  Thermophiles, the last group of archaea, can withstand acid environments that are exposed to high temperatures (Mukherjee, 2009).

When we talk about bacteria in the clinical context, we are usually referring to the eubacteria. These microorganisms have a very complex structure and can be found in neutral conditions such as food, the human body and almost everywhere around. Eubacteria are divided into three phyla: cyanobacteria, spirochetes and proteobacteria.  Cyanobacteria are photosynthetic organisms that are usually found in aquatic environments. They can use light energy to produce their own food and produce oxygen as a by-product. Spirochetes are gram negative bacteria that may be parasitic or symbiotic with their hosts. They can survive on their own (not parasitic). Another group is the proteobacteria which consists of a wide variety of species  are free living and are responsible for nitrogen fixation in the soil (Mukeherjee 2009).

Biochemical Characteristics

Biochemically, archaea are more similar with eukaryotes than eubacteria. They have a complex RNA polymerase in terms of subunits like the eukaryote nuclear polymerase. They also have amino acid sequence homology with some eukaryotic subunits. Although both archaea and eubacteria have operons which they transcribe to polycistronic mRNA, the protein initiator amino acid for archaea is methionine while eubacteria have N-formyl methionine. It has also been found out that eubacteria do not synthesize protein in response to diphtheria toxin, while archaea do (Fox, 2010). Eubacteria are susceptible to antibiotics, while archaea are not affected by such substances. In addition, eubacteria contain an rRNA loop, which binds to ribosomal protein  and have a common arm of tRNA, while archaea don’t (Tortora, 2007).

Cell membrane Components

All eubacteria, except the genera Mycoplasma and Chlamydia possess a peptidoglycan layer. This layer in the organism’s cell wall contains a sugar called muramic acid which cannot be found anywhere else in nature. The counterpart of this bacteria  in archaebacteria is pseudomurein. Instead of N-acetylmuramic acid, pseudomurein has N-acetylglucosamine and N-acetyltalosaminuronic acid as its components (Fox, 2010). Membrane lipids of these two major bacterial groups are also different. Those in archaea are composed of branched carbon chains that are attached to glycerol by ether linkage, while the membrane lipids in eubacteria are straight and unbranched (Tortora 2007).

To sum up everything, archaebacteria live under extreme conditions, are simple single celled organisms and lack a peptidoglycan layer, while eubacteria live in neutral environments, are more complex than archaea, have peptidoglycan in their cell membrane and are studied more extensively by human beings.

With today’s advances in technology, we are able to classify organisms according to their various phenotypic and even genetic properties. Continued research in this field is very much essential in understanding what these microorganisms can do to harm or benefit the world.

 

Works Cited

  • Fox, A. (2010, May 18). The Bacterial Cell. Retrieved November 3, 2011, from Microbiology and Immunology Online: University of South Carolina School of Medicine: http://pathmicro.med.sc.edu/fox/protype.htm
  • Mukherjee, P. (2009, September 18). Difference Between Eubacteria and Archaebacteria. Retrieved November 3, 2011, from Difference Betwee.net: http://www.differencebetween.net/science/health/difference-between-eubacteria-and-archaebacteria/
  • Tortora, G. J., Funke, B. R., & Case, C. L. (2007). Microbiology: An Introduction. Singapore: Pearson Education South Asia Pte Ltd.
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