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Chemoautotrophs and photosynthetic eubacteria

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Chemoautotrophs and photosynthetic eubacteria

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Chemoautotrophs and photosynthetic eubacteria

  1. 1. troph = nourishment auto = self chemo = chemical chemoutotrophs
  2. 2.  derive energy from chemical reactions  synthesize all necessary organic compounds from carbon dioxide  use inorganic energy sources, such as hydrogen sulfide, elemental sulfur, ferrous iron, molecular hydrogen, and ammonia  They can be also called as chemolithoautotrophs .
  3. 3.  Most chemoautotrophs are bacteria or archaea that live in hostile environments such as deep sea vents, active volcanoes and are the primary producers in such ecosystems  A unique characteristic of these chemoautotrophic bacteria is that they thrive at temperatures high enough to kill other organisms
  4. 4.  use inorganic reduced compounds as a source of energy  This process is accomplished through oxidation and ATP synthesis  Most chemolithotrophs are able to fix carbon dioxide (CO2) through the Calvin Cycle, a metabolic pathway in which carbon enters as CO2 and leaves as glucose
  5. 5. Chemolithotrophy: Energy from the Oxidation of Inorganic Electron Donors
  6. 6.  Carry out respiration by coupling the oxidation of an inorganic compound to the reduction of membrane-bound electron carriers: e–  electron transport chain  proton motive force  ATP synthesis 8 inorganic electron donor  protons pumped out most ATP produced by oxidative phosphorylation
  7. 7.  sulfur oxidizers  nitrifying bacteria  iron oxidizers Hydrogen oxidizers.  Anammox Bacteria
  8. 8. ATP has a free energy of -31.8 kJ/mol
  9. 9.  2H2 + 02  2H20 (1)  2 H2 + C02  <CH20 > + H20 (2)  6H2 + 202 + CO2  <CH20> +5 H20 (3)
  10. 10. Hydrogen Bacteria Ralstonia eutropha is a gram-negative soil bacterium of the betaproteobacteria class
  11. 11.  Many species of nitrifying bacteria have complex internal membrane systems that are the location for key enzymes in nitrification: ammonia monooxygenase which oxidizes ammonia to hydroxylamine, and nitrite oxidoreductase, which oxidizes nitrite to nitrate.
  12. 12.  Nitrifying bacteria are widespread in the environment, and are found in highest numbers where considerable amounts of ammonia are present (areas with extensive protein decomposition, and sewage treatment plants).  They thrive in lakes and streams with high inputs of sewage and wastewater because of the high ammonia content.
  13. 13.  Nitrification in nature is a two-step oxidation process of ammonium (NH4 + or ammonia NH3) to nitrate (NO3 -) catalyzed by two ubiquitous bacterial groups. The first reaction is oxidation of ammonium to nitrite by ammonium oxidizing bacteria (AOB) represented by Nitrosomonas species. The second reaction is oxidation of nitrite (NO-) to nitrate by nitrite-oxidizing 2 bacteria (NOB), represented by Nitrobacter species.
  14. 14.  Ammonia oxidation: It is a complex process that requires several enzymes, proteins and presence of oxygen. The key enzymes, necessary to obtaining energy during oxidation of ammonium to nitrite are: ammonia monooxygenase (AMO) and hydroxylamine oxidoreductase (HAO)
  15. 15. In anoxic ammonia oxidation, the nitrifying bacteria can use ammonia and nitrite as electron donors, a process called nitrification. The ammonia-oxidizing bacteria produce nitrite.
  16. 16.  Nitrite produced in first step autotrophic nitrification is oxidized to nitrate by nitrite oxidoreductase (N0R)(2). It is a membrane-associated iron-sulfur molybdoprotein, and is part of an electron transfer chain which channels electrons from nitrite to molecular oxygen. The molecular mechanism of oxidation nitrite is less described than oxidation ammonium.
  17. 17. The ammonia-oxidizing bacteria produce nitrite which is then oxidized by the nitrite-oxidizing bacteria to nitrate.
  18. 18. Nitrosococcus NH 3 NO2 – Nitrobacter NO2 –  NO3 – No single bacterium oxidizes ammonia all the way to nitrate.
  19. 19.  Nitrobacter  Nitrobacter is a genus of mostly rod-shaped, gram-negative, and chemoautotrophic bacteria. Nitrobacter plays an important role in the nitrogen cycle by oxidizing nitrite into nitrate in soil  Nitrosomonas  Nitrosomonas is a genus comprising rod shaped chemoautotrophic bacteria. This bacteria oxidizes ammonia into nitrite as a metabolic process. Nitrosomonas are useful in treatment of industrial and sewage waste and in the process of bioremediation
  20. 20. “White Streamers” color due to sulfur granules in cells
  21. 21. Fe Oxidation at low pH The pH effect on Fe+2 concentrations is reflected in the energy yield: Fe+2 + O2 + H+  Fe+3 + H2O Thiobacillus ferrooxidans, an acidophilic iron-oxidizer, pH optimum for growth of 2 to 3 Contribute to formation of acid mine drainage. Thiobacillus-type [rods] in yellow floc from acid water
  22. 22. The iron bacteria are chemolithotrophs that use ferrous iron (Fe2+) as their sole energy source.
  23. 23. Most iron bacteria grow only at acid pH and are often associated with acid pollution from mineral and coal mining.
  24. 24. Extensive development of insoluble ferric hydroxide in a small pool draining a bog in Iceland. Iron deposits such as this are widespread in cooler parts of the world and are modern counterparts of the extensive bog iron deposits of earlier geological eras
  25. 25. Anammox - Anaerobic ammonium 36 NH4 + + NO2 oxidation -  N2 + 2 H2O
  26. 26. Brocadia anammoxidans Anammox bacteria: Planctomyces group Brocadia anammoxidans "Candidatus Brocadia anammoxidans" is a bacterial member of the order Planctomycetes and therefore lacks peptidoglycan in its cell wall, has a compartmentalized cytoplasm.
  27. 27.  Enrichment culture of the anammox bacterium Kuenenia stuttgartiensis
  28. 28. Eubacteria, known as "true bacteria," are prokaryotic (lacking nucleus) cells that are very common in human daily life.
  29. 29.  They have a single strand of DNA.  Eubacteria Lack a nuclear membrane.  Eubacteria have phili which help transfer DNA.  The cytoplasm is filled with ribosomes.  Eubacteria lack a nuclei or nucleus .  Some Eubacteria have a flagella. A tail like structure to help them move.  Eubacteria have a plasma membrane to hold the insides of the cell in place.  They are enclosed by a cell wall that provides as a rigid wall to keep the cells shape.
  30. 30.  Phototrophic bacteria are a group of bacteria, whose energy for growth is derived from sunlight and their source of carbon comes from carbon dioxide or organic carbon. There are two groups of phototrophic bacteria, i.e., anoxygenic phototrophic bacteria and oxygenic phototrophic bacteria.
  31. 31. Cyanobacteria or blue-green bacteria  oxygenic photosynthesis Purple bacteria  anoxygenic photosynthesis Green bacteria anoxygenic photosynthesis
  32. 32.  Cyanobacteria’s are photosynthetic bacterias,also referred as bluegreen algae.  Have similar chlorophyll a to the plants.  Oxygenic phototrophy(unique in evolution)
  33. 33. Nostoc
  34. 34. anabaena
  35. 35. Carry out anoxygenic photosynthesis; no O2 evolved Morphologically diverse group Genera fall within the Alpha-, Beta-, or Gammaproteobacteria Contain bacteriochlorophylls and carotenoid pigments Produce intracytoplasmic photosynthetic membranes with varying morphologies  - allow the bacteria to increase pigment content  - originate from invaginations of cytoplasmic membrane
  36. 36. Liquid Cultures of Phototrophic Purple Bacteria Rhodospirillum rubrum Rhodobacter sphaeroides Rhodopila globiformis
  37. 37. Purple Sulfur Bacteria Purple Non-sulfur Bacteria
  38. 38. › Use hydrogen sulfide (H2S) as an electron donor for CO2 reduction in photosynthesis › Sulfide oxidized to elemental sulfur (So) that is stored as globules either inside or outside cells  Sulfur later disappears as it is oxidized to sulfate (SO2-) 4 › The family Chromatiaceae contains the purple-sulphur bacteria
  39. 39. Photomicrographs of Purple Sulfur Bacteria Chromatium okenii Thiospirillum jenense Thiopedia rosea Ectothiorhodospira mobilis
  40. 40. › Many can also use other reduced sulfur compounds, such as thiosulfate (S2O3 2-) › All are Gammaproteobacteria › Found in illuminated anoxic zones of lakes and other aquatic habitats where H2S accumulates, as well as sulfur springs
  41. 41. Blooms of Purple Sulfur Bacteria Lamprocystis roseopersicina Algae (Spirogyra) Thiocystis sp. Chromatium sp.
  42. 42. › Originally thought organisms were unable to use sulfide as an electron donor for CO2 reduction, now know most can › Most can grow aerobically in the dark as chemoorganotrophs › Some can also grow anaerobically in the dark using fermentative or anaerobic respiration › Most can grow photoheterotrophically using light as an energy source and organic compounds as a carbon source › All in Alpha- and Betaproteobacteria › The family Rhodospirillaceae contains the purple non-sulphur bacteria
  43. 43. Phaeospirillum fulvum Rhodoblastus acidophilus Rhodobacter sphaeoides
  44. 44. Green Non- Sulphur Bacteria Green Sulfur Bacteria
  45. 45. GREEN SULFUR BACTERIA These are obligatory phototrophic bacteria Reproduction is from binary fission mode. Photosynthesis is achieved using bacteriophyll c,d or e. They use H2S as electron donor for CO2 fixation.  Granules of elemental sulphur are deposited only outside the cells and the sulphur can eventually be oxidized to SO4(-2).
  46. 46.  . In this group of bacteria flexible filaments are formed and so these are also called as the green flexi bacteria. They possess gliding mobility. Most of them do not have gas vesicles. The organisms are mainly photoorganotrophic, as the purple non-sulphur bacteria, but they can also grow as photolithotrophs as the purple non-sulphur bacteria, but they can also grow as photolithotrophs with H2S as the electron donor. In the dark they can grow aerobically as chemoheterotrophs.

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