1. Reference Chapter 2,5,6, 7, 8, 9 Microbiology by Tortora, Funke & Case
Microbial Nutrition
Gary Andersen
Reference Chapter 2,5,6, 7, 8, 9 Microbiology by Tortora, Funke & Case
Metabolism
Chemical
Substances
Cell
Growth

2. What do microbes eat?

3. Composition and Nutrition of Cells
96% of cells are composed of HCNOPS.
Macronutrients are nutrients required in larger quantities. (carbohydrates, proteins, fats and other CHO molecules)
Micronutrients are nutrients required in trace amounts. (Mn, Zn, Cu, Ni)

4. Where are the Elements Used?

5. Sources of Nutrients Carbon – CO2 in air and rocks organisms
Nitrogen – N2 in air, NO2, NO3, NH4 in soil and water  organisms (NH3)
Oxygen – O2 in air, inorganic salts SO4, PO4, NO3, H2O
Hydrogen – Water, Organic compounds in organisms
Phosphorus – Rocks and minerals  organisms
Sulfur – Rocks and minerals  organisms

6. Microbe Nutritional Types
Autotrophs – “Self feeder”
Photoautotrophs – Photosynthetic (energy from light)
Chemoautotrophs – Energy from simple inorganic chemicals
Methanogens – Metabolize H2 and CO2 into CH4 and H2O
Heterotrophs – “Other feeder”
Chemoheterotroph – Obtain carbon and energy from organic compounds. CnH2nOn + O2  CO2 + H2O + ATP (Adenosine tri-phosphate)
Saprobe – Free living organisms that feed on dead organisms
Parasite – Derive nutrients from the tissues of hosts.

7. Microbial Clean-Up: The 1989 Exxon Valdez oil spill left great quantities of pooled oil on sites in the Gulf of Alaska, such as on Green Island

8. Microbial Clean-Up: Bioremediation in 1989, by the application of nutrients (nitrogen and phosphorus) to the shoreline accelerated the bacterial biodegradation of the oil into carbon dioxide and water

9. Microbial Clean-Up: In 1991, the area was surveyed and found to be mostly cleared of oil, with no further treatment recommended

10. How do Microbes Eat?

11. Transport Mechanisms Passive Transport
Diffusion – Movement of molecules from a high concentration to a low concentration.
Facilitated Diffusion- diffusion assisted by conformational change in a protein molecule.
Osmosis – Diffusion of water through a semipermeable membrane
Active Transport – Moving particles against the diffusion gradient using membrane proteins and expending energy.
Endocytosis – Engulfing with cell membrane and forming a vacuole.
Phagocytosis – Engulfing of cells or particles by the cell membrane
Pinocytosis – Engulfing of liquids by the cell membrane

12. Passive Transport
Osmosis animation:
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13. Comparing Solutions
Hypertonic Solution – Higher solute concentration. Cells in hypertonic solutions lose water and the cell membrane shrinks away from the cell wall. (Salt on a slug)
Hypotonic Solution – Lower solute concentration. Cells in hypotonic solutions take on water and swell. (Prune wrinkles of skin)
Isotonic Solutions – Solutions that have reached an equilibrium with a cell or another solution. The concentration of solute is equal and the diffusion of water proceeds at equal rates.
(See page 93 of text for what happens to a cell in hypertonic
and hypotonic solutions.)

14. Animations of Passive and Active Transport

15. How do microbes metabolize nutrients? Fermentation and Respiration

16. Enzymes Provide a surface on which reactions take place
Active site: the area on the enzyme surface where the enzyme forms a loose association with the substrate
Substrate: the substance on which the enzyme acts
Enzyme-substrate complex: formed when the substrate molecule collides with the active site of its enzyme
Enzymes generally have a high degree of specificity
Endoenzymes (intracellular)/exoenzymes (extracellular)

17. The Action of Enzymes on Substrates to Yield Products

18. Each substrate binds to an active site, producing an enzyme-substrate complex. The enzyme helps a chemical reaction occur, and one or more products are formed

19. Competitive Regulation and Inhibition of Enzymes

20. Noncompetitive (allosteric) inhibition of enzymes

21. Factors Influencing Enzymes
Temperature pH
Concentration of substrate, product, and enzyme

22. Relationship between temperature and enzyme activity
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23. Microbes and Environmental Factors
Temperature pH
Oxygen
Pressure
Extremophiles – Organisms that can survive under extreme environmental conditions. An interesting source of chemical products.
Interesting Website on Extremophiles and Chemical Products:

24. Temperature
Classification
Psychrophile
Mesophile
Thermophile

25. Temperature Thermophiles – organisms that grow at >45 degrees C.
Pyrococcus fumarii is an example of a thermophile that can survive at 113 C.
Thermal pool

26. Grand Prismatic Spring

27. pH Acidophiles – grow at low pH levels. (1-2)
14 Alkaline 13 12 11 10 9 8
7 Neutral 6 5 4 3 2 1
0 Acidic
Acidophiles – grow at low pH levels. (1-2)
Alkalinophiles – live at high pH levels. (9-10)

28. Pressure
Barophiles – organisms that grow at elevated pressure ( x air pressure). (Found in ocean depths often in thermal vents)

29. Presence of Oxygen Aerobe – Organism able to use O2 in metabolism.
Anaerobe – Organism unable to use O2 in metabolism.
Obligate aerobes - oxygen mandatory Obligate anaerobes - oxygen toxic
Facultative anaerobes – Aerobe that can also live without O2
Microaerophiles - low oxygen levels required.
Aerotolerant - anaerobic metabolism, oxygen not toxic

30. Microbial Processing of Oxygen
Step 1: O2- + O2- + 2H+  H2O2 + O2 (Catalyzing enzyme is Superoxide dismutase)
Step 2: H2O2 + H2O2  2H2O + O2 (Catalyzing enzyme is Catalase)

31. Living without Oxygen….Glucose Fermentation Pathways
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32. Glucose Fermentation Net and practical results
Cells get chemical energy (ATP)
Fermentation products are natural waste products useful to humans:
Fermented beverages
Bread
Cheese
Yogurt

33. Using fermentation metabolism to identify microbes: A positive (yellow) mannitol-fermentation test. This test distinguishes the pathogenic Staphylococcus aureus
(MSA)
Test
Mannitol
Salts
Agar

34. Comparing Aerobic Respiration with Anaerobic Fermentation
Fermentation yields small amount of ATP (2)
Partial oxidation of carbon atoms (6 C  3 C)
Respiration
Substrate molecules are completely oxidized to C02 (6 C  1 C)
Far higher yield of ATP (36)
The Krebs Cycle and Electron Transport Chain

35. Final Electron Acceptors: Aerobic respiration, anaerobic respiration, and fermentation have different final electron acceptors

36. Microbe Growth Binary or transverse fission
Generation or Doubling Time – the time required for parent cell to form two new daughter cells.

37. Microbe Growth
Lag – new cells require adjustment and enlargement. The cells are not multiplying rapidly.
Log or exponential – maximum rate of growth

38. Microbe Growth 2
Stationary – death and multiplication balance out. Depleted nutrients and waste buildup.
Death – limiting factors intensify. May last a long time.

39. Calculating Growth of Cells
Nf = Final population
Ni = Initial population
2n = # cells in generation
n = generation number
Nf = (Ni)2n
Use the table in the handout from the Talaro Appendix A-2 to
calculate the number of cells in the generation.

42. Measuring Growth Serial Dilutions, Plate Counts and Turbidity
Measuring growth turbidity plate counts

43. Calculation of the number of bacteria per milliliter of culture using serial dilution
Pour plate: made by first adding 1.0ml of diluted culture to 9ml of molten agar
Spread plate: made by adding 0.1ml of diluted culture to surface of solid medium

44. Counting colonies using a bacterial colony counter

45. Bacterial colonies viewed through the magnifying glass against a colony-counting grid

46. Countable number of colonies (30 to 300 per plate)
Which of these plates would be the correct one to count? Why?
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47. The Petroff-Hausser Counting Chamber

48. Turbidity, or a cloudy appearance, is an indicator of bacterial growth in urine in the tube on the left

49. A Spectrophotometer: This instrument can be used to measure bacterial growth by determining the degree of light transmission through the culture

50. The Streak Plate Method uses agar plates to prepare pure cultures

51. A Streak Plate of Serratia marcescens
A Streak Plate of Serratia marcescens. Note the greatly reduced numbers of growth /colonies in each successive region

52. Types of Culture Media
Natural Media: In nature, many species of microorganisms grow together in oceans, lakes, and soil and on living or dead organic matter
Synthetic medium: A medium prepared in the laboratory from material of precise or reasonably well-defined composition
Complex medium: contains reasonably familiar material but varies slightly in chemical composition from batch to batch (e.g. peptone, a product of enzyme digestion of proteins)
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53. Commonly Used Media Yeast Extract Casein Hydrolysate Serum Blood agar
Chocolate agar

54. Selective, Differential, and Enrichment Media
Selective medium: encourages growth of some organisms but suppresses growth of others
(e.g. antibiotics)
Differential medium: contains a constituent that causes an observable change (e.g. MacConkey agar)
Enrichment medium: contains special nutrients that allow growth of a particular organism that might not otherwise be present in sufficient numbers to allow it to be isolated and identified

55. Three species of Candida can be differentiated in mixed culture when grown on CHROMagar Candida plates

56. Identification of urinary tract pathogens with
differential media (CHROMagar)

57. Ecological Associations
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58. Symbiosis (Mutualism)
Obligatory
Both organisms benefit.
Examples: algae + fungus = lichen, termites and trychonympha (a protist)
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59. Symbiosis (Commensalism)
One organism benefits and the other is not harmed.
Examples: Non-pathogenic bacteria on our skin; satellitism between bacteria colonies.

60. Symbiosis (Parasitism)
One organism benefits and the other is harmed.
Examples: Pathogenic organisms on their host. Plasmodium vivax a protozoan parasite causing malaria.

61. Non Symbiotic (Synergism)
Substance A
Free living organisms.
Both benefit
The relationship is optional.
Examples: Shared metabolism; nitrogen fixing bacteria in the soil and plants
Microorganism 1
Substance B
Microorganism 2
Substance C
Microorganism 3
End Product used by all three
microorganisms

62. Non Symbiotic (Antagonism)
Free living organisms
Organisms compete for resources.
One organism secretes a substance toxic to the other.
Example: Ruminal cellulose digesting bacteria and fungi
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63. End of Microbial Nutrition Slides