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Elements of Microbial Nutrition, Ecology


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Elements of Microbial Nutrition, Ecology

  1. 1. Foundations in Microbiology Chapter 7 PowerPoint to accompany Fifth Edition Talaro Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  2. 2. Elements of Microbial Nutrition, Ecology and Growth Chapter 7
  3. 3. Microbial nutrition <ul><li>Macronutrients – required in large quantities; play principal roles in cell structure & metabolism </li></ul><ul><ul><li>proteins, carbohydrates </li></ul></ul><ul><li>Micronutrients or trace elements – required in small amounts; involved in enzyme function & maintenance of protein structure </li></ul><ul><ul><li>manganese, zinc, nickel </li></ul></ul>
  4. 4. Nutrients <ul><li>Inorganic nutrients – atom or molecule that contains a combination of atoms other than carbon and hydrogen </li></ul><ul><ul><li>metals and their salts (magnesium sulfate, ferric nitrate, sodium phosphate), gases (oxygen, carbon dioxide) and water </li></ul></ul><ul><li>Organic nutrients - contain carbon and hydrogen atoms and are usually the products of living things </li></ul><ul><ul><li>methane (CH 4 ), carbohydrates, lipids, proteins, and nucleic acids </li></ul></ul>
  5. 5. Chemical composition of cytoplasm <ul><li>70% water </li></ul><ul><li>proteins </li></ul><ul><li>96% of cell is composed of 6 elements </li></ul><ul><ul><li>Carbon </li></ul></ul><ul><ul><li>Hydrogen </li></ul></ul><ul><ul><li>Oxygen </li></ul></ul><ul><ul><li>Phosphorous </li></ul></ul><ul><ul><li>Sulfur </li></ul></ul>
  6. 6. Obtaining Carbon <ul><li>Heterotroph – an organism that must obtain carbon in an organic form made by other living organisms such as proteins, carbohydrates, lipids and nucleic acids </li></ul><ul><li>Autotroph - an organism that uses CO 2 , an inorganic gas as its carbon source </li></ul><ul><ul><li>not dependent on other living things </li></ul></ul>
  7. 7. Nitrogen <ul><li>Main reservoir is nitrogen gas (N 2 ) </li></ul><ul><li>79% of earth’s atmosphere is N 2 </li></ul><ul><li>Nitrogen is part of the structure of proteins, DNA, RNA & ATP – these are the primary source of N for heterotrophs </li></ul><ul><li>Some bacteria & algae use inorganic N nutrients (NO 3 - , NO 2 - , or NH 3 ) </li></ul><ul><li>Some bacteria can fix N 2 </li></ul><ul><li>Regardless of how N enters the cell, it must be converted to NH 3 , the only form that can be combined with carbon to synthesis amino acids, etc. </li></ul>
  8. 8. Oxygen <ul><li>major component of carbohydrates, lipids and proteins </li></ul><ul><li>plays an important role in structural & enzymatic functions of cell </li></ul><ul><li>component of inorganic salts (sulfates, phosphates, nitrates) & water </li></ul><ul><li>O 2 makes up 20% of atmosphere </li></ul><ul><li>essential to metabolism of many organisms </li></ul>
  9. 9. Hydrogen <ul><li>major element in all organic compounds & several inorganic ones (water, salts & gases) </li></ul><ul><li>gases are produced & used by microbes </li></ul><ul><li>roles of hydrogen </li></ul><ul><ul><li>maintaining pH </li></ul></ul><ul><ul><li>forming H bonds between molecules </li></ul></ul><ul><ul><li>serving as the source of free energy in oxidation-reduction reactions of respiration </li></ul></ul>
  10. 10. Phosphorous <ul><li>main inorganic source is phosphate (PO 4 -3 ) derived from phosphoric acid (H 3 PO 4 ) found in rocks & oceanic mineral deposits </li></ul><ul><li>key component of nucleic acids, essential to genetics </li></ul><ul><li>serves in energy transfers (ATP) </li></ul>
  11. 11. Sulfur <ul><li>widely distributed in environment, rocks, sediments contain sulfate, sulfides, hydrogen sulfide gas and sulfur </li></ul><ul><li>essential component of some vitamins and the amino acids: methionine & cysteine </li></ul><ul><li>contributes to stability of proteins by forming disulfide bonds </li></ul>
  12. 12. Important mineral ions <ul><li>Potassium </li></ul><ul><li>Sodium </li></ul><ul><li>Calcium </li></ul><ul><li>Magnesium </li></ul><ul><li>Iron </li></ul>
  13. 13. Growth factors <ul><li>organic compounds that cannot be synthesized by an organism & must be provided as a nutrient </li></ul><ul><ul><li>essential amino acids, vitamins </li></ul></ul>
  14. 14. Metabolizing organic cpds organic chemoheterotrophs sunlight organic photoheterotrophs Simple inorganic chemicals CO 2 chemoautotrophs sunlight CO 2 photoautotrophs Energy source Carbon source
  15. 15. <ul><li>Saprobes – decompose dead organisms, recycle elements, release enzymes to digest materials </li></ul><ul><li>Parasites – utilize tissues and fluids of a living host and cause harm </li></ul>
  16. 16. saprobes
  17. 17. Transport mechanisms <ul><li>Passive transport –do not require energy, substances exist in a gradient and move from areas of higher concentration towards areas of lower concentration </li></ul><ul><ul><li>Diffusion </li></ul></ul><ul><ul><li>Osmosis - water </li></ul></ul><ul><ul><li>Facilitated diffusion – requires a carrier </li></ul></ul><ul><li>Active transport – require energy and carrier proteins, gradient independent </li></ul><ul><ul><li>Carrier-mediated active transport </li></ul></ul><ul><ul><li>Group translocation – transported molecule chemically altered </li></ul></ul><ul><ul><li>Bulk transport – endocytosis, exocytosis, pinocytosis </li></ul></ul>
  18. 18. diffusion
  19. 19. osmosis
  20. 21. passive transport
  21. 22. Active transport
  22. 23. Bulk transport
  23. 24. Environmental influences on microbial growth <ul><li>temperature </li></ul><ul><li>oxygen requirements </li></ul><ul><li>pH </li></ul><ul><li>electromagnetic radiation </li></ul><ul><li>barometric pressure </li></ul>
  24. 25. 3 cardinal temperatures <ul><li>Minimum temperature – lowest temperature that permits a microbe’s growth and metabolism </li></ul><ul><li>Maximum temperature – highest temperature that permits a microbe’s growth and metabolism </li></ul><ul><li>Optimum temperature – promotes the fastest rate of growth and metabolism </li></ul>
  25. 26. 3 temperature adaptation groups <ul><li>Psychrophiles – optimum temperature below 15 o C, capable of growth at 0 o C </li></ul><ul><li>Mesophiles – optimum temperature 20 o -40 o C, most human pathogens </li></ul><ul><li>Thermophiles – optimum temperature greater than 45 o C </li></ul>
  26. 27. 3 temperature adaptation groups
  27. 28. Oxygen requirements
  28. 30. Microbial associations <ul><li>Symbiotic – organisms live in close nutritional relationships; required by one or both members </li></ul><ul><ul><li>Mutualism – obligatory, dependent; both members benefit </li></ul></ul><ul><ul><li>Commensalism – commensal member benefits, other member not harmed </li></ul></ul><ul><ul><li>Parasitism – parasite is dependent and benefits; host is harmed </li></ul></ul>
  29. 31. Microbial associations <ul><li>Non-symbiotic – organisms are free-living; relationships not required for survival </li></ul><ul><ul><li>Synergism – members cooperate and share nutrients </li></ul></ul><ul><ul><li>Antagonism – some member are inhibited or destroyed by others </li></ul></ul>
  30. 32. Binary Fission
  31. 33. Population growth
  32. 34. Growth curve
  33. 35. Growth curve <ul><li>Lag phase – “flat” period of adjustment, enlargement; little growth </li></ul><ul><li>Exponential growth phase – a period of maximum growth will continue as long as cells have adequate nutrients & a favorable environment </li></ul><ul><li>Stationary phase – rate of cell growth equals rate of cell death cause by depleted nutrients & O 2 , excretion of organic acids & pollutants </li></ul><ul><li>Death phase – as limiting factors intensify, cells die exponentially in their own wastes </li></ul>
  34. 36. Turbidity
  35. 37. Direct microscopic count
  36. 38. Electronic counting