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By: Sailen Talukdar Biotech dept .,2 nd sem Roll no: 15 Exam roll no: 178

Presentation. on. Archaebacteria. Under the guidance of P.J. Handique Sir GAUHATI UNIVERSITY. By: Sailen Talukdar Biotech dept .,2 nd sem Roll no: 15 Exam roll no: 178. Archaebacteria. Introduction Discovery Types Structure Application. Discovery.

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By: Sailen Talukdar Biotech dept .,2 nd sem Roll no: 15 Exam roll no: 178

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  1. Presentation on • Archaebacteria Under the guidance of P.J. Handique Sir GAUHATI UNIVERSITY By: Sailen Talukdar Biotech dept.,2ndsem Roll no: 15 Exam roll no: 178

  2. Archaebacteria • Introduction • Discovery • Types • Structure • Application

  3. Discovery Based on 16S and 18S rRNA sequence data, Woese proposed a third kingdom • life on earth is made of 3 primary lineages which he referred to as domains [Woese,(1990) PNAS 87:4576-4579]. • Eubacteria (Eu = good or true) • Archeae (Archeae = ancient) and • Eukarya (Carya = nut or kernel)

  4. phylogenetically divided into three kingdoms

  5. Structural Attributes • Shape and size • spheres, spiral,rods, lobed, plate-shaped, irregular-shaped • exist as single cells, as aggregates or form filaments. • diameter is 0.1-15 µm and the length can be up to 200 µm. Cell multiplication binary fission,budding, fragmentation… Cell Walls Most do contain cell walls (except -Thermoplasma species) Schematic representations and electron micrograph of a gram-positive archaeum e.g. Methanobacterium (b)a gram-negative archaeum e.g. Thermoproteus. CW =cell wall, CM = cytoplasmic membrane, CPL = cytoplasm and SL = surface layer.

  6. Lipids and Cell Membranes • Archael lipids are hydrocarbons (isoprenoid hydrocarbons)not fatty acids • branched (straight chain in bacteria & eukaryotes) and linked to glycerol by ether bonds (ester linked in bacterial & eukaryotes).

  7. Functional Attributes Habitat and ecology • found in extreme environments ( anaerobic, saline to hypersaline,high temperature and cold temperature habitats) (constitutes 34% of microbial biomass in the Antarctic surface waters). • Some are symbionts in animal digestive tracts. Nutrition, Physiology and Metabolism aerobes, anaerobes & facultative anaerobes. growth temperature : mesophilic to hyperthermophilic pH growth : very acidic (<0.5) to neutral Chemoorganaotrophs : Use organic substrates as energy source for growth. Autotrophy : eg. Methanogens use Acetyl-CoA or some modification to fix CO2

  8. Molecular Attributes Genomes • chromosome is a single, circular DNA molecule & extrachromosomal elements (eg plasmids) are found in Archaea. • Genomic resistance to thermal denaturation & genomic structural intergrity in extreme halophiles is related to high intracellular salt concentrations (solutes) • Introns found in archael 23S and 16S rRNA and tRNA genes

  9. Transcription • has one type of RNA polymerase (similar to the eukaryote RNA polymerase POL II) • Archael promoters have an A-T rich sequence at -32 to -25 bp upstream of the transcriptional start: the consensus sequence resembles a eukaryotic TATA box. Translation Lack of formylmethionine.

  10. 3 Archaebacterial Groups • Methanogens • Halophiles • Thermoacidophiles

  11. Methanogens • anaerobic bacteria that get energy by turning H2 and CO2 into methane (CH4) • live in mud, swamps, and the guts of cows, humans, termites and other animals

  12. Halophiles • are organisms that live in environments with extremely high salt concentrations • some extreme halophiles can live in solutions of 35 % salt. (seawater is only 3% salt!) • halophile means “salt loving” • most halophiles are aerobic and heterotrophic; others are anaerobic and photosynthetic, containing the pigment bacteriorhodopsin

  13. Diversity of Halophilic Organisms • halophiles are found in salt lakes, salt marshes, subterranean salt deposits, dry soils, salted meats, hypersaline seas, and salt evaporation pools • the Red Sea was named after the halobacterium that turns the water red during massive blooms.

  14. Halophile Environments solar salterns Owens Lake, Great Salt Lake, coastal splash zones, Dead Sea

  15. Thermoacidophiles • Like temperature and pH extremes • Hot = up to 110ºC • Cold = down to 1ºC • Acid = as low as pH 2 • Alkali = as high as pH 9 • they are chemoautotrophs, using H2S • the first Extremophile was found about 30 years ago

  16. Thermophile Environments Hydrothermal Vents in the ocean, and Obsidian Pool in Yellowstone National Park

  17. Alan Hills Ice Field: Antarctica Psychrophile Environments

  18. Thermophile Applications • many industrial processes involve temperature extremes, which is a problem for most enzymes • Enzymes to work on foods that need to be refrigerate • PCR reactions

  19. Chemical Extremes • Acidophiles - Acidic • Again thermal vents and some hot springs • Alkaliphiles - Alkaline • Soda lakes in Africa and western U.S. • Halophiles - Highly Salty • Natural salt lakes and manmade pools • Sometimes occurs with extreme alkalinity

  20. Acidophile Environments

  21. Alkaliphiles • “Stonewashed” pants • Alkaliphilic enzymes soften fabric and release some of the dyes, giving worn look and feel • Detergents • Alkaliphilic enzymes can work with detergents

  22. Alkaliphile Environments e.g. Mono Lake alkaline soda lake, pH 9, salinity 8%

  23. Special Techniques for Survival While external environments are “extreme”, internal cell environments are “normal”. • Ways to protect the cell: • Acidophiles and Alkaliphiles sometimes excrete protective substances and enzymes • Acidophilesoften lack cell wall • Some moderate halophiles have high concentrations of a solute inside to avoid “pickling” • Many microbes contain unusual enzymes

  24. Interesting Facts • The term “red herring” comes from the foul smell of salted meats that were spoiled by halobacterium. • There have been considerable problems with halophiles colonizing leather during the salt curing process. • Halobacterium( Halophile) replaces the silicon chip. • Computer chip made up of thin layer of bacteriorhodopsin

  25. Future Applications Many possible applications using halophiles are being explored such as: • genetically engineering halophilic enzymes, encoding DNA into crops to allow for salt tolerance • treatment of waste water

  26. Refferences • M.Ciaramella et al, Molecular biology of extremophiles, World Journal of Microbiology and Biotechnology, Vol 11, pp 71-84, 1995 • Brown, J.W. et al, Gene Structure, Organisation and Expression in Archaebacteria.CRC Critical Reviews in Microbiology, Vol 16, No. 4, 1989 • http://genomebiology.com

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