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Microbial Diversity

Microbial Diversity. Morphological. Not much to see!. Morphological Diversity. Microbial Diversity – Genetic. Microbiology!!!. Functional Diversity. Biochemical/metabolic E.g. Rhodoferax ferroreducens Microbial fuel cells Pass electrons to anode, produce power from waste

stephen-daugherty
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Microbial Diversity

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  1. Microbial Diversity • Morphological Not much to see!

  2. Morphological Diversity

  3. Microbial Diversity – Genetic Microbiology!!!

  4. Functional Diversity • Biochemical/metabolic • E.g. Rhodoferax ferroreducens • Microbial fuel cells • Pass electrons to anode, produce power from waste • E.g. Vibrio cholerae • Severe diarrhea Rhodoferax ferroreducens Vibrio cholerae

  5. Habitat Diversity • Environmental conditions • Where in the world? • Other worlds? Yellowstone

  6. Microbial Diversity – Overview • Oxygen requirements (metabolism) and tolerance (habitat) • Nutritional diversity (metabolic) • Carbon, energy, and electron sources • Habitat diversity • Extremophiles

  7. Oxygen • Toxic for some • Requirement for some • Like us!

  8. Metabolism Catabolism Anabolism Provides energy for Uses Uses Degradative pathways Biosynthetic pathways Both bi-directional Amphibolic pathways

  9. Catabolism Overview • Humans, animals, many microbes

  10. A bunch of steps!!! Catabolism:Oxidation-Reduction C6H12O6 • Electron source (reduced) • Aka “energy source” • Electron acceptor (oxidized) • Aka “terminal electron acceptor” (TEA) • End products: • Oxidized electron source • Reduced electron acceptor + O2 CO2 + H2O

  11. Glycolysis • The oxidation of glucose to pyruvic acid, produces 2 ATP and 2 NADH+ 2 ATP + 2 NADH+

  12. PreparatoryStage Glucose Glucose 1 • 2 ATPs used Glucose 6-phosphate Fructose 6-phosphate Fructose 1,6-diphosphate Glyceraldehyde 3-phosphate (GP) Dihydroxyacetone phosphate (DHAP) Figure 5.12.1

  13. 6 1,3-diphosphoglyceric acid 7 3-phosphoglyceric acid 8 2-phosphoglyceric acid 9 Phosphoenolpyruvic acid (PEP) 10 Pyruvic acid Figure 5.12.2 EnergyProducing Stage • 4 ATP produced • 2 NADH+ produced

  14. Overall: Glucose + 2 ADP + 2 PO4– + 2 NAD+2 pyruvic acid + 4 ATP + 2 NADH + 2H+

  15. Intermediate Step • Pyruvic acid is oxidized and decarboyxlated Figure 5.13.1

  16. Krebs Cycle • Aka: • TCA cycle • Citric acid cycle • 1 ATP • 2 NADH+ • 1 FADH2 Figure 5.13.2

  17. Respiration • Oxidation liberates electrons – used to produce NADH+ and FADH2 • Electrons then passed along an electron transport chain (ETC) • ATP generated by oxidative phosphorylation • Proton motive force • ATPase • 1 glucose  38 ATP

  18. Electron Transport Chain • Proton motive force • Proton gradient • Ion gradient • PMF = DpH + DY

  19. Uses of PMF

  20. ATPase

  21. Respiration • Aerobic respiration: TEA is O2 • Anaerobic respiration: TEA is not O2 • Yields less energy than aerobic • Why?

  22. Anaerobic Rs E0’ = electropotential (Voltage) DG aDE0’ The greater the difference in E0’ between e- source and TEA, the more energy available

  23. Aerobic Vs. Anaerobic • E. coli • Which produces more PMF? • Why?

  24. Chemoorganotrophs Diversity: Bacteria, Archaea vs. Eukarya

  25. Fermentation • Produces ATP only from substrate-level phosphorylation (SLP) • Far less energy than Rs • 1 glucose  2 ATP • Does not use Krebs cycle or ETC for energy generation • Uses an organic molecule as the terminal electron acceptor • Need to recycle the NAD+

  26. Types of Fermentation • Eukaryotes and prokaryotes

  27. Types of Fermentation Figure 5.18b

  28. Laboratory Tests Labs 3C and 8

  29. Metabolism Switchers • Human cells, yeast • Aerobic Rs and Fm • Pseudomonas aeruginosa • Aerobic Rs and Rs of NO3- • E. coli • Aerobic Rs, Anaerobic Rs, Fm

  30. Oxygen Requirement Diversity Knows these terms!

  31. Oxygen Thioglycolate broth resazurin

  32. Culturing Anaerobes Anaerobic glove box Gas Pack

  33. Toxicity of Oxygen • We live in a toxic world! • Atmosphere full of a toxic, explosive gas: O2 • Every breath generates chemicals that damage membranes, oxidize macromolecules (such as DNA) and kill cells • Aerobes, such as ourselves, must detoxify!

  34. Toxic Forms of Oxygen • O2 – already very reactive • Singlet oxygen (electrons shifted to higher levels) • Created photo- and bio-chemically • Carotenoids protect cells

  35. Toxic Forms of Oxygen • Superoxide anion (O2-) and hydrogen peroxide (H2O2) • Produced as by-products during respiration • Hydroxyl radical (OH.) • Produced by ionizing radiation (e.g. UV) • Extremely reactive • Antioxidant molecules can protect • E.g. carotenoids

  36. Enzymatic Protection Lab 3 Staphylococcus Streptococcus

  37. Catalase Test

  38. Obligate Aerobes • Usually • Catalase+ • Peroxidase+ • SOD+ • E.g. • Most eukaryotes • Azotobacter • Many Bacillus sp.

  39. Microaerophiles • Usually • Catalase- • Peroxidase+ • SOD - variable • E.g. • Helicobacter pylori • Magnetospirillum magnetotacticum

  40. Facultative Aerobes • Usually • Catalase+ • Peroxidase+ • SOD+ • E.g. • E. coli • Shigella • Pseudomonas aeruginosa

  41. Aerotolerant Anaerobes • Strictly fermentive metabolism • Can grow in presence of azide • Usually • Catalase- • Peroxidase+ • SOD+ • E.g. • LAB • Streptococcus, Enterococcus, Lactobacillus

  42. Obligate Anaerobes • Usually • Catalase- • Peroxidase- • SOD- • E.g. • Clostridium (fermenter) • Desulfovibrio vulgaris (anaerobic Rs)

  43. Lab Tests • Catalase • Oxidase (tests for cytochrome c) • EMB and MacConkey agar (lactose fermentation, acid production) • Lactose and glucose broth • Azide broth, KF agar

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