Archaebacteria

The word Archae came from the Greek word Arkhaion, which means “Ancient”.

Archae is also the Latin name for Prokaryotic Cells. Archaea that growing the hot water of the Hot Spring in Yellowstone National Park produce a bright yellow color.

Archaebacteria are known to be the oldest living organisms on earth. They belong to the kingdom Monera and are classified as bacteria because they resemble bacteria when observed under a microscope. Apart from this, they are completely distinct from prokaryotes. However, they share slightly common characteristics with the eukaryotes.

1. S .Palaniananth 1 st msc microbiology submitted to mrs. vijayasanthi murugan Archaebacteria Launch Launch

2. Archae - Bacteria 2 microbial taxonomy and diversity The word Archae came from the Greek word Arkhaion , which means “ Ancient” . Archae is also the Latin name for Prokaryotic Cells. Archaea that growing the hot water of the Hot Spring in Yellowstone National Park produce a bright yellow color. Archaebacteria are known to be the oldest living organisms on earth. They belong to the kingdom Monera and are classified as bacteria because they resemble bacteria when observed under a microscope. Apart from this, they are completely distinct from prokaryotes . However, they share slightly common characteristics with the eukaryotes.

3. History 3 microbial taxonomy and diversity Carl Woese was an American Microbiologist and Biophysicist. Archaebacteria were not recognized as a distinct form of life from bacteria until 1977, when Carl Woese and George Fox determined this through RNA studies. Dr. Carl Woese spearheaded a study of evolutionary relationships among prokaryotes. Instead of physical characters, he relied on rRNA sequences to determine how closely related these microbes.

4. Archaebacteria 4 microbial taxonomy and diversity

5. 5 microbial taxonomy and diversity Basis for Comparison Archaea Bacteria Definition Archaea is a group of primitive prokaryotes that based on their distinct characteristics form a separate domain from bacteria and eukaryotes. Bacteria are single-celled primitive organisms that form a domain of organisms diverse in shape, size, structure, and even habitats. Habitat Most archaea are extremophiles and are found in extreme environments like the deep sea, mountains, hot springs, salt brine, etc. Bacteria reside in different habitats ranging from soil, water to inside living, and non-living organisms. Cell wall The archaeal cell wall is made up of pseudopeptidoglycan and lack D-aminoacids and N-acetylmuramic acid. The bacterial cell wall is made up of peptidoglycan consisting of N- acetylmuramic acid and D-amino acids. Membrane lipid The fatty acids in membrane lipids of archaea are bound to glycerol by ether bonds. The fatty acids in membrane lipids of bacteria are bound to glycerol by ester bonds. glucose oxidation Archaea do not use glycolysis or Kreb’s cycle for glucose oxidation but follow metabolic pathways similar to these. Glycolysis and Kreb’s cycle are important metabolic pathways in bacteria for glucose oxidation.

6. 6 microbial taxonomy and diversity Basis for Comparison Archaea Bacteria Photosynthesis Archaea do not perform oxygen-generating photosynthesis but are phototrophs, that use sunlight as a source of energy. Many bacteria containing photosynthetic pigments can perform photosynthesis to prepare their own food. Types Archaea are divided into different groups like Methanogens, Thermophiles, and Halophiles on the basis of their characteristics. Bacteria are divided as Gram-negative and Gram-positive based on their response to Gram staining. Flagella Archaeal flagella, also termed archaella, are synthesized by adding subunits at the base. Bacterial flagella are hollow and are assembled by adding subunits moving from the central pore towards the tip of the flagella. Reproduction Archaea reproduce by fission, budding, and fragmentation. Sporulation doesn’t occur in archaea. Some bacteria are capable of forming spores that help them survive extreme conditions for a particular period of time. tRNA Thymine is absent in the t-RNA of archaea. Thymine is present in the t-RNA of bacteria. tmRNA tmRNA (transfer messenger RNA) is found in archaea. tmRNA is found in bacteria.

7. 7 microbial taxonomy and diversity

8. 8 microbial taxonomy and diversity Basis for Comparison Archaea Bacteria Chromosomes Introns are present in the chromosomes of archaea. Introns are absent in the chromosomes of bacteria. RNA polymerase RNA polymerase in archaea is complex with more than eight polypeptides. They might even have multiple RNA polymerases. Bacterial RNA polymerase is simple, with four polypeptides. Pathogenicity Archaea are non-pathogenic. Bacteria might be pathogenic or non-pathogenic. Examples Thermosphaera aggregans , Staphylothermus marinus ,  Sulfolobus tokodaii . Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus, Salmonella   Typhi .

9. Characteristics of Archaebacteria 9 microbial taxonomy and diversity Archaebacteria are obligate or facultative anaerobes , i.e., they flourish in the absence of oxygen and that is why only they can undergo methanogenesis . The cell membranes of the Archaebacteria are composed of lipids. The rigid cell wall provides shape and support to the Archaebacteria. It also protects the cell from bursting under hypotonic conditions. The cell wall is composed of Pseudomurein ,  which prevents archaebacteria from the effects of Lysozyme. Lysozyme is an enzyme released by the immune system of the host, which dissolves the cell wall of pathogenic bacteria. These do not possess membrane-bound organelles such as nuclei, endoplasmic reticulum, mitochondria, lysosomes or chloroplast. Its thick cytoplasm contains all the compounds required for nutrition and metabolism.

10. Characteristics of Archaebacteria 10 microbial taxonomy and diversity They can live in a variety of environments and are hence called extremophiles . They can survive in acidic and alkaline aquatic regions, and also in temperature above boiling point. They can withstand a very high pressure of more than 200 atmospheres. Archaebacteria are indifferent towards major antibiotics because they contain plasmids which have antibiotic resistance enzymes. The mode of reproduction is asexual, known as binary fission. They perform unique gene transcription. The differences in their ribosomal RNA suggest that they diverged from both prokaryotes and eukaryotes.

11. CLASSIFICATION 11 microbial taxonomy and diversity Archaea can be divided by two different categories: Phylum Crenarchaeota Euryarchaeota Korarchaeota Behavior Methanogens Halophiles Thermophiles

12. 12 microbial taxonomy and diversity Crenarchaeota The Crenarchaeota are Archaea, which exist in a broad range of habitats. They are tolerant to extreme heat or high temperatures . They have special proteins that help them to function at temperatures as high as 230 degrees Celsius. They can be found in deep-sea vents and hot springs, regions with superheated water. These include thermophiles, hyperthermophiles, and thermoacidophiles . Euryarchaeota These can survive under extremely alkaline conditions and have the ability to produce methane, unlike any other living being on earth. These include methanogens and halophiles. Korarchaeota They possess the genes common with  Crenarchaeota  and  Euryarchaeota.  All three are believed to have descended from a common ancestor. These are supposed to be the oldest surviving organism on earth. These include hyperthermophiles.

13. Types of Archaea 13 microbial taxonomy and diversity Methanogens and Halophiles are part of the Euryarchaeota phylum Thermophiles are part of the Crenarchaeota phylum. Methanogens Methanogens are microorganisms that produce methane as metabolic by product in anoxic conditions. They are strictly anaerobic organisms & are killed when exposed to O2 . They reduce co2 , using H2 , & release CH3 in swamps & marshes that is called marsh gas. Occurance : Many live in mud at the bottom of lakes and swamps because it lacks oxygen They are also found in the gut of some herbivores like cows , humans• dead & decaying matter

14. 14 microbial taxonomy and diversity .• Importance : They are added to biogas reactors for production of CH4 gas for cooking & sewage treatment plants. Examples Methanofollis aqukemaris , M. ethanolicus M. formosanus.Mliminatans

15. 15 microbial taxonomy and diversity Halophiles: Halophiles :-= salt phil = loving The halophilic organisms require salty environment forsurvival

16. 16 microbial taxonomy and diversity Occurrence : they are found in salts lakes & areas where evaporation of séa water occurs such as the Great Lake in the U.S. and the Dead Sea Salt Can live in water with salt concentrations exceeding 15% The ocean's concentration is roughly 4% Example : Halo bacterium which includes several species, found in salt lakes & high saline ocean environments Halobacterium salinarum H. denitrificans & H halobium

17. Thermophiles 17 microbial taxonomy and diversity Thermophiles are found in extremely hot or extremely acidic locations  (up to 252°F) They can be found at hydrothermal vents, hot springs, acidic mine leakage, and volcanoes. All thermophiles require hot water but differ in other habitat needs. some thrive in only acidic water, others require Sulphur or calcium carbonate & others live in alkaline springs. Depending on characteristics which it may possess, They can be described with more specific terms such as- Thermoacidophile (heat and acid lover) they have both aerobic and anaerobic species. Hyperthermophile (extreme heat lover).- Pyrolobus fumarii , currently holds the record for high temperature growth, it can grown in temperatures up to 113°C

18. Thermophiles 18 microbial taxonomy and diversity

19. Respiration/Nutrition 19 microbial taxonomy and diversity Different types of archaea obtain food and energy differently Some are phototrophs, some are lithotrophs , and some are organotrophs Even within the different groups of archaea, there is variation, but the majority of the organisms get energy the same way Methanogens They are lithotrophs Lithotrophs -  use an inorganic source of energy But use an organic source of carbon. They  take in hydrogen as their source of energy, and carbon dioxide as their source of carbon, and they combine these to create methane . Some of them can also use organic carbon as well. They are  strictly anaerobic  meaning barely any oxygen will kill them.

20. 20 microbial taxonomy and diversity Halophiles Halophiles use sunlight as energy , but not through photosynthesis, so they are considered phototrophs instead of autotrophs. They are  primarily aerobic  and they use organic materials for their source of carbon, but  they don’t use carbon dioxide . Thermophiles Thermophiles can either be lithotrophs or organotrophs Lithotrophs - use inorganic substances for energy Organotrophs - use organic substances for energy They  take in sulfur as their energy source , and they can use either organic forms of carbon or carbon dioxide as their carbon source

21. Reproduction, Growth, and Development 21 microbial taxonomy and diversity Most archaea reproduce through a process called  binary fission . All of the archaea’s genetic material is replicated Then, through  cytokinesis , they divide to form a new organism. The created archaea has the  same genetic information  as the original one unless there are mutations. Evolution occurs so slowly for these organisms because  mutations are the only way that variation occurs .

22. Importance of archaebacteria 22 microbial taxonomy and diversity Methanogens are used for the production of methane which is a rich source of energy Preparation of glycoproteins & proteins from archaeal cultures are used to increase body's defense against infection Halophilic archaea are used to prescreen antitumor drugs active on eukaryotic proteins Thermophilic archaea are used in PCR Extraction of Metals : Acidophilic Archaea Extract gold, copper and cobalt from their ores. Methane Gas Production: Methanogenic Archaean decompose grow in biogas fermenters e cow dung into methane gas as a by-product.

23. Importance of archaebacteria 23 microbial taxonomy and diversity Role in chemical cycles: Play important role in carbon cycle, nitrogen cycle, Sulphur cycle etc. Help in reasearches : Their ability to tolerate extreme conditions helps researchers learn about the climatic conditions, environment and their survival on ancient earth. Anti- biotics : Archaea host a new class of potentially useful antibiotics.

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