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Microbiology

Microbiology. Chapter 7. Nutrient Cycling. Carbon Hydrogen Nitrogen Oxygen Phosphorus Sulfur. C. H. N. O. P. S. Nutrient Cycling. Do not take for granted that nutrients must enter the web of life How is N 2 or CO 2 useful to you? You are a carbon based life form!!

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Microbiology

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  1. Microbiology Chapter 7

  2. Nutrient Cycling • Carbon • Hydrogen • Nitrogen • Oxygen • Phosphorus • Sulfur C H N O P S

  3. Nutrient Cycling • Do not take for granted that nutrients must enter the web of life • How is N2 or CO2 useful to you? • You are a carbon based life form!! • How does carbon enter your life in a useful form? • You need nitrogen for building DNA and RNA

  4. Inorganic vs. Organic • Inorganic – nutrient is an atom or simple molecule that contains the elements carbon, oxygen, nitrogen, phosphorous, hydrogen, and sulfur • Organic – nutrients contain at least some combination of carbon and hydrogen

  5. Nutrient Cycling • Oxygen, Hydrogen and Phosphorous occur widely in metabolically available forms • Why • The major available forms of C and N are extremely stable (unreactive) • Why

  6. Nutrient Cycling

  7. Three Categories of Nutrient Cycling • Hydrologic cycle • Water • Atmospheric cycles • Nitrogen and carbon • Sedimentary cycles • Phosphorus, carbon and sulfur

  8. Hydrologic Cycle Atmosphere precipitation onto land 111,000 wind-driven water vapor 40,000 evaporation from land plants (evapotranspiration) 71,000 evaporation from ocean 425,000 precipitation into ocean 385,000 surface and groundwater flow 40,000 Oceans Land

  9. volcanic action photosynthesis TERRESTRIAL ROCKS weathering Carbon Cycle diffusion Atmosphere Bicarbonate, carbonate Terrestrial rocks Land food webs Marine food webs Soil water Peat, fossil fuels Marine Sediments

  10. Source of Carbon • Where an organism acquires its carbon from determines if it is an autotrophic organism or a heterotrophic organism • Why? • What organism are considered heterotrophic • What organism are considered autotrophic

  11. Autotrophs • Photoautotrophs • Use the energy from sunlight to remove electrons from H2O to make reducing equivalence • Oh my God what is a reducing equivalence this is a big word!!! Don’t panic • Reducing equivalence – a molecule that can transfer electrons and hydrogen to make simple molecules (CO2) more complex (Glucose)

  12. Autotrophs • Chemoautotrophs (lithoautotrophs) • No sunlight or organic nutrients • Use enzymes to remove electrons from inorganic substances H2 gas, H2S, sulfur, and iron to make reducing equivalence • Just like land plants these will transfer electrons and hydrogen to CO2 to make simple organic molecules • These molecules make a modest amount of energy to drive the synthetic processes of the cell

  13. Tube Worms at Ocean Vents

  14. Heterotrophs • Must obtain carbon in its organic form • Where do these organic molecules come from? • Heterotrophs begin with a molecule that is high in energy (like a candy bar) • Heterotrophs remove electrons from food to make ATP • Heterotrophs are not concerned with making reducing equivalence • Why?

  15. Chemoheterotrophic • Saprobes – free living eat dead matter • Use extracellular enzymes • Usually not pathogenic • Natural habitat not another organism • Can be opportunistic pathogens

  16. Chemoheterotrophic • Parasites – derive nutrients from host • Ectoparasites or endoparasites • Obligate parasites – syphilis spirochete • Obligate intracellular • Rickettsis – energy • Malaria – hemoglobin • Virus – genetic and metabolic

  17. Carbon and Energy Sources

  18. Nitrogen Cycle

  19. Nitrogen Fixation • N2 is converted to metabolically useful forms by only a few strains of bacteria of the genus Rhizobium • Live in symbiotic relationships with root nodule cells of legumes • This is an expensive energetic process N2 + 8H+ + 8e- + 16ATP + 16H2O 2NH3 + H2 + 16ADP + 16Pi

  20. Phosphorus Cycle mining FERTILIZER excretion GUANO agriculture weathering uptake by autotrophs uptake by autotrophs weathering MARINE FOOD WEBS DISSOLVED IN OCEAN WATER DISSOLVED IN SOILWATER, LAKES, RIVERS LAND FOOD WEBS death, decomposition death, decomposition leaching, runoff sedimentation setting out uplifting over geologic time ROCKS MARINE SEDIMENTS

  21. Table 7.2

  22. Osmosis

  23. Diffusion • Passive Transport • Osmosis • Facilitated • Osmosis • What type of solutions are fresh water bacteria and amebas living in • How do these creatures live in this type of environment?

  24. Active Transport • Protein pumps – against concentration gradient • Endocytosis • Pinocytosis • Phagocytosis • exocytosis

  25. Environmental Factors That Influence Growth • Five main factors which influence growth • Temperature • Gas Requirements • pH • Pressure • Salt • Miscellaneous Factors • UV light • X Rays

  26. Temperature • Why do micro-organism assume ambient temperature of their environment?

  27. Cardinal Range and Optimum Temperature • Limited • Typus rickettsia 32ºC to 38ºC • Rhinoviruses 33ºC to 35ºC • Broad • S Aureus 6ºC to 46ºC • E Faecalis 0ºC to 44ºC

  28. Psychrophile • Optimum temperature below 15ºC • Bacteria which can grow slowly in cold but have an optimum temperature above 20ºC • Psychrotrophs • Facultative psychrophiles • S Aureus • Listeria monocytogenes • Why are these of concern to the medical community?

  29. Mesophiles • Grow at intermediate temperature • 10ºC to 50ºC • Optimum temperature • 20ºC to 40ºC • Thermoduric microbes can survive short exposure to high temperatures are common contaminants of heated or pasteurized foods • Giardia, Bacillus, and Clostridium

  30. Thermophile • Optimum temperature above 45ºC • Where might these species live • Direct sunlight • Ocean vents • Volcanos • Most eukaryotic thermophiles live above 60ºC • Some bacterial thermophiles can live from 80ºC to 250ºC

  31. Gas Requirements • O2 Requirements • Aerobe • Facultative Anaerobe • Microaerophile • Anaerobe • Some body sites present anaerobic pockets where colonization and infection can occur • Oral cavity • Large intestine • Traumatic injuries • CO2 Requirements • Capnophiles grow best at higher CO2

  32. Oxygen Requirements

  33. Anaerobic Chamber

  34. Oxygen Problems? • Organisms which use oxygen can generate really harmful reactive oxygen species (ROS) which can damage cellular components • These ROS are caused by a bypass reaction in the ETC

  35. Oxygen Problems? • Normal Reaction • Food + O2 CO2 + H20 • Bypass Reaction • FAD:H2 + O2 O2-(ROS) e- removed from food end up on water Bypass reaction e- end up on free oxygen Electron carrier in ETC

  36. Problem Solved • Super Oxide Dismutase • 2O-2 + 2H+ H2O2 + O2 • Catalase • 2H2O2 2H20 + O2 • These combined reactions recycle ROS to free oxygen which is not toxic

  37. Osmotic Pressure • Most microbes exist under hypotonic conditions • Halophiles require high concentrations of salt • Grow in 25% to 9% salt • These archaea have significant modification in their cell walls and will lyse in hypotonic habitats • Some are osmotolerant – resistant to salt • S. Aureus

  38. Life in the Extremes Algae Euglena mutabilis Thrives in acidic waters with high heavy metal concentration. Can also exist in wide range of pH and temperature. Methanogens – primitive archaea chemoautotrophs Live in all kinds of environments from inside cows to deep ocean vents 4H2 + CO2 CH4 + 2H2O

  39. Ecological Associations • Incorrect to think of bacteria behaving as individual cells • The tendency of microbes to form biofilm communities is an ancient and effective survival strategy

  40. Ecological Associations • Blood Agar is a type of agar which contains whole RBC of organisms (sheep, human, etc) • How is Haemophilus able to grow on blood agar • What type of relationship is this?

  41. Quorum Sensing • Quorum sensing occurs in several stages and monitors cell density, secretion of chemical signals, and genetic activation • Steps • Bacteria attracted to surface and settle • Settling stimulates secretion which binds bacteria to substrate • Cells release inducer molecules which enter cells and stimulate gene expression

  42. Stages in Quorum Sensing

  43. Examples of Biofilms • Pseudomonas • Tenacious lung biofilms • S. Aureus • Films on inanimate medical devices and wounds • Streptococcus • Initial colonists on teeth surfaces

  44. Binary Fission

  45. Population Mathmatics

  46. Growth Curve

  47. Methods of Analyzing Population Growth • Turbidity • Coulter Counter • Cytometer – bacteria counted on a grid slide under a microscope

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