Chemoautotrophs and photosynthetic eubacteria

Chemoautotrophs and photosynthetic eubacteria

1. Chemoautotrophs   and Photosynthetic Eubacteria

2. crea ted by , Rishab Dhar

3. chemoutotrophs

4. Intoduction to Chemoautotrophs 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 .

5. Ecology 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

6. Chemolithotrophs 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

7. Chemolithotrophy: Energy from the Oxidation of Inorganic Electron Donors

8. 8 Carry out respiration by coupling the oxidation of an inorganic compound to the reduction of membrane-bound electron carriers: most ATP produced by oxidative phosphorylation inorganic electron donor  protons pumped out  proton motive force  ATP synthesis e –  electron transport chain

9. Chemolithotrophs can be classified as: sulfur oxidizers nitrifying bacteria iron oxidizers Hydrogen oxidizers . Anammox Bacteria

10. Chemolithotrophs: Energy yields ATP has a free energy of -31.8 kJ/mol

11. Hydrogen oxidizing bacteria or Knallgas -bacteria they are capable of using hydrogen (H 2 ) as a source of energy While several mechanisms of anaerobic hydrogen oxidation processes are known (e.g. sulfate reducing- and acetogenic bacteria), hydrogen can also be used as an energy source aerobically

12. Hydrogen is used in the oxygen-hydrogen reaction serving the generation of energy in (equation 1) and the fixation of CO 2 to the level of cellular material in(equation 2). The average ratio of hydrogen uptake over the uptake of carbon dioxide (H 2 /CO 2 )in(equation 3) 2H 2 + 0 2  2H 2 0 (1) 2 H 2 + C0 2  <CH 2 0 > + H 2 0 (2) 6H 2 + 20 2 + CO 2  <CH 2 0> +5 H 2 0 (3)

13. Hydrogen Bacteria Ralstonia eutropha is a gram-negative soil bacterium of the betaproteobacteria class

14. Nitrifying Bacteria They are chemoautotrophic or chemolithotrophs depending on the genera ( Nitrosomonas , Nitrosococcus ,   Nitrobacter , Nitrococcus ) bacteria that grow by consuming inorganic nitrogen compounds

15. 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.

16. Ecology of nitrifying bacteria 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 .

17. Oxidation of ammonia to nitrate Nitrification in nature is a two-step oxidation process of ammonium (NH 4 +  or ammonia NH 3 ) to nitrate (NO 3 - ) 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 2 - ) to nitrate by nitrite-oxidizing bacteria (NOB), represented by  Nitrobacter  species .

18. First step nitrification 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 )

19. Ammonia Oxidation 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.

20. Second step nitrification 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.

21. Nitrification and Ammonia Oxidation (cont) The ammonia-oxidizing bacteria produce nitrite which is then oxidized by the nitrite-oxidizing bacteria to nitrate.

22. Ammonium- and Nitrite-Oxidizing Bacteria Nitrosococcus NH 3  NO 2 – Nitrobacter NO 2 –  NO 3 – No single bacterium oxidizes ammonia all the way to nitrate.

23. 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

24. Sulfur oxydizing Bacteria Sulfur oxidation involves the oxidation of reduced sulfur compounds (such as sulfide H 2 S), inorganic sulfur (S ), and thiosulfate (S 2 O 3 2- − ) to form  sulfuric acid  (H 2 SO 4 ). A classic example of a sulfur-oxidizing bacterium is  Beggiatoa

25. Sox-dependent (shown in red) and Sox-independent (shown in blue) sulfur oxidation pathways of deep-sea vent chemoautotrophs . These pathways are used by Epsilonproteobacteria and Gammaproteobacteria ( . The gene cluster of  P. pantotrophus  coding for sulfur-oxidizing ability (Sox) comprises at least two transcriptional units with 15 genes. Seven genes,  soxXYZABCD , code for proteins essential for sulfur oxidation in vitro).

26. Overall Sulfur Oxidation process is HS - + O 2  SO 4 -2 + H + Microbes’ environment may be pH < 2 . ‘S’ oxidation mediated by chemolithotrophs using reduced S compounds as e- donors. HS- oxidation can occur under anaerobic conditions

27. Beggiatoa sp. are organisms live in sulfur -rich environments . They are named after the Italian medic and botanist F.S. Beggiato .

28. “ White Streamers ” color due to sulfur granules in cells

29. Ferrous iron (Fe2+)oxidizing Bacteria Ferrous iron (Fe +2 ) oxidizing bacteria uses an electron donor linked with oxygen reduction High levels of Fe +2 are needed But: aerobic conditions, neutral pH iron is essentially all solid Fe +3 oxides Two adaptations for use of Fe +2 : Low pH and/or low O 2

30. Fe Oxidation at low pH The pH effect on Fe +2 concentrations is reflected in the energy yield: Fe +2 + O 2 + H +  Fe +3 + H 2 O 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

31. The iron bacteria are chemolithotrophs that use ferrous iron (Fe 2+ ) as their sole energy source.

32. Most iron bacteria grow only at acid pH and are often associated with acid pollution from mineral and coal mining.

33. 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

34. Anammox Anammox , an abbreviation for ANaerobic AMMonium OXidation , is a globally important microbial process of the nitrogen cycle . [1] The bacteria mediating this process were identified in 1999, and at the time were a great surprise for the scientific community. [2] It takes place in many natural environments and anammox is also the trademarked name for the anammox -based ammonium removal technology that was developed

35. Anammox bacteria contain a hydrazine-containing intracellular organelle called the anammoxasome , surrounded by highly compact (and unusual)  ladderane  lipid membrane. These lipids are unique in nature, as is the use of hydrazine as a metabolic intermediate. Anammox organisms are autotrophs although the mechanism for carbon dioxide fixation is unclear. Because of this property, these organisms could be used in industry to remove nitrogen in  wastewater treatment  processes. [9]   Anammox has also been shown have widespread occurrence in anaerobic aquatic systems and has been speculated to account for approximately 50% of nitrogen gas production in the ocean

36. 36 NH 4 + + NO 2 -  N 2 + 2 H 2 O Anammox - Anaerobic ammonium oxidation

37. Brocadia anammoxidans 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. Anammox bacteria: Planctomyces group

38. Enrichment culture of the anammox bacterium Kuenenia stuttgartiensis

39. Application The application of the anammox process lies in the removal of ammonium in wastewater treatment and consists of two separate processes. The first step is partial nitrification ( nitritation ) of half of the ammonium to nitrite by ammonia oxidizing bacteria : 4NH 4 + + 3O 2 → 2NH 4 + + 2NO 2 - + 4H + + 2H 2 O The resulting ammonium and nitrite are converted in the anammox process to dinitrogen gas by anammox bacteria NH 4 + + NO 2 - → N 2 + 2 H 2 O Both processes can take place in 1 reactor where two guilds of bacteria form compact granules

40. Eubacteria Eubacteria , known as "true bacteria," are prokaryotic (lacking nucleus) cells that are very common in human daily life.

41. Physiology /Anatomy 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.

42. Phototrophic bacteria 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.  

43. Anoxygenic phototrophic bacteria are the gram-negative bacteria that can use light as an energy source and they are anaerobic as they do not evolve oxygen during photosynthesis. Aerobic anoxygenic phototrophic bacteria are another group, which are obligate aerobes that capture energy from light by anoxygenic photosynthesis . Oxygenic phototrophic bacteria can also use light as an energy source but they are aerobic as they evolve oxygen in a manner similar to as that of green plants.

44. Photosynthetic Eubacetria Those eubacteria which can generate their own food using photosynthesis are called as Photosynthetic Eubacetria

45. THREE distinct and well-defined groups of Photosynthetic eubacteria .

46. CYANOBACTERIA Cyanobacteria’s are photosynthetic bacterias,also referred as bluegreen algae. Have similar chlorophyll a to the plants. Oxygenic phototrophy (unique in evolution)

47. They often form blooms in polluted water bodies. Some of these organisms can fix atmospheric nitrogen in specialised cells called heterocysts , e.g., Nostoc and Anabaena .

48. Cyanobacteria’s can also be counted in chemoaututrophs bacteria oxidises various inorganic substances such as nitrates,nitrites and ammonia and use the released energy for the production of ATP They play a great role in recycling nutrients like nitrogen,sulphur,phosphorus and iron. Cyanobacteria’s usually does this by using callesd as heterocyst.

49. Nostoc

50. anabaena

51. Purple phototrophic bacteria Purple Phototrophic Bacteria Carry out anoxygenic photosynthesis; no O 2 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

52. Liquid Cultures of Phototrophic Purple Bacteria Rhodospirillum rubrum Rhodobacter sphaeroides Rhodopila globiformis

53. Purple phototrophic bacteria Purple Sulfur Bacteria Purple Non-sulfur Bacteria

54. Purple Sulfur Bacteria Use hydrogen sulfide (H 2 S) as an electron donor for CO 2 reduction in photosynthesis Sulfide oxidized to elemental sulfur (S o ) that is stored as globules either inside or outside cells Sulfur later disappears as it is oxidized to sulfate (SO 4 2- ) The family Chromatiaceae contains the purple-sulphur bacteria

55. Photomicrographs of Purple Sulfur Bacteria Chromatium okenii Thiospirillum jenense Thiopedia rosea Ectothiorhodospira mobilis

56. Purple Sulfur Bacteria (cont’d) Many can also use other reduced sulfur compounds, such as thiosulfate (S 2 O 3 2- ) All are Gammaproteobacteria Found in illuminated anoxic zones of lakes and other aquatic habitats where H 2 S accumulates, as well as sulfur springs

57. Blooms of Purple Sulfur Bacteria Lamprocystis roseopersicina Algae ( Spirogyra ) Chromatium sp . Thiocystis sp .

58. Purple Nonsulfur Bacteria Originally thought organisms were unable to use sulfide as an electron donor for CO 2 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

59. Representatives of Purple Nonsulfur Bacteria Phaeospirillum fulvum Rhodoblastus acidophilus Rhodobacter sphaeoides

60. GREEN BACTERIA Green phototrophic bacteria contain bacteriochlorophyll types c or d and minor amounts of bacteriochlorophyll a. The pigments involved in photosynthesis are located in membrane-bound vesicles within the cell. Cultures are generally green or brown in colour

61. Green Bacteria Green Non- Sulphur Bacteria Green Sulfur Bacteria

62. 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 H 2 S 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).

63. Chlorobium tapedium (a green sulfur bacteria)

64. Photosynthesis process in green sulfur bacteria

65. GREEN NON-SULFUR BACTERIA .  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 H 2 S as the electron donor. In the dark they can grow aerobically as chemoheterotrophs.

66. Fig :- green nonsulfur bacteria- chloroflexi