Unit 8034 Culture microorganisms and control microbial growth By Elysia Butler
Nutritional Requirements <ul><li>All living organisms require nutrients to grow.  </li></ul><ul><li>Microorganisms get the...
Nutrients <ul><li>Carbon – Used in the creation of proteins, carbohydrates and lipids. </li></ul><ul><li>Nitrogen – Utilis...
Nutrients <ul><li>Sulphur – Important with regards to amino acids. </li></ul><ul><li>Phosphorus – Important with regards t...
Hetero / Auto - trophs <ul><li>Heterotrophs - Obtain the majority of their carbon as organic compounds by either directly ...
Chemo / Photo - trophs <ul><li>Chemotrophs – Obtain their energy from chemical compounds. </li></ul><ul><li>Phototrophs – ...
Selective Media <ul><li>Encourage growth of specific types of microorganisms </li></ul><ul><li>Inhibits growth of specific...
Differential Media <ul><li>Can grow more than one type of microorganism </li></ul><ul><li>Can compare one type to another ...
Differential Example <ul><li>To the right is a photograph of different bacterium grown on differential media </li></ul><ul...
Limiting Microbial Growth Physically <ul><li>Microbial growth can be limited by altering one or all of the following to a ...
Temperature <ul><li>Psychrophiles – organisms that grow best between 15C – 20C </li></ul><ul><li>Mesophiles – organisms th...
Gaseous Atmosphere <ul><li>Aerobic – Typically require oxygen at levels of 21%  </li></ul><ul><li>Anaerobic – Don’t requir...
Limiting Microbial Growth Chemically <ul><li>Adding antimicrobial agents to media will inhibit the growth of specific orga...
Iodine <ul><li>Kills bacteria and endospores on human skin </li></ul><ul><li>Presence of organic material decreases effect...
Formaldehyde Gas <ul><li>Kills bacteria and endospores in enclosed areas </li></ul><ul><li>Kills vegetative cells quicker ...
Phenolic Compounds <ul><li>Bacteriostatic  (Inhibits growth but does  not kill)  at low concentrations </li></ul><ul><li>B...
Antibiotic Mode of Action <ul><li>Can work by affecting the Peptidoglycan in the Cell Wall </li></ul><ul><li>Inhibits cros...
Antibiotic mode of action <ul><li>Some antibiotics kill pathogens by affecting the Cytoplasmic Membrane </li></ul><ul><li>...
Limiting Antibiotic Effectiveness <ul><li>Mutant cells that are non-responsive to the antibiotic. </li></ul><ul><li>Wrong ...
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Microbial Growth

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NZQA Unit 8034 - Culture microorganisms and control microbial growth

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Microbial Growth

  1. 1. Unit 8034 Culture microorganisms and control microbial growth By Elysia Butler
  2. 2. Nutritional Requirements <ul><li>All living organisms require nutrients to grow. </li></ul><ul><li>Microorganisms get their nutrients in the form of chemical elements which exist in nature as either organic or inorganic compounds. </li></ul>
  3. 3. Nutrients <ul><li>Carbon – Used in the creation of proteins, carbohydrates and lipids. </li></ul><ul><li>Nitrogen – Utilised in amino acids, which make up proteins. </li></ul><ul><li>Hydrogen and Oxygen – Generally make up the organic compounds that are ingested or absorbed. </li></ul>
  4. 4. Nutrients <ul><li>Sulphur – Important with regards to amino acids. </li></ul><ul><li>Phosphorus – Important with regards to adenosine triphosphate and nucleic acids. </li></ul><ul><li>Other elements are also required for the nutrition of microorganisms but in smaller quantities. </li></ul>
  5. 5. Hetero / Auto - trophs <ul><li>Heterotrophs - Obtain the majority of their carbon as organic compounds by either directly absorbing it through the environment or by ingesting other heterotrophs or autotrophs. </li></ul><ul><li>Autotrophs -Obtain their carbon source as inorganic elements through the environment. </li></ul>
  6. 6. Chemo / Photo - trophs <ul><li>Chemotrophs – Obtain their energy from chemical compounds. </li></ul><ul><li>Phototrophs – Obtain the majority of their energy from a light source. </li></ul><ul><li>Some organisms cant be classified solely as a chemotroph or a phototroph as they have the ability to adapt to the surrounds eg R. rubrum </li></ul>
  7. 7. Selective Media <ul><li>Encourage growth of specific types of microorganisms </li></ul><ul><li>Inhibits growth of specific microorganisms </li></ul><ul><li>Sometimes used for both of the above purposes. </li></ul>
  8. 8. Differential Media <ul><li>Can grow more than one type of microorganism </li></ul><ul><li>Can compare one type to another </li></ul><ul><li>Varying appearance of microorganisms on the media </li></ul><ul><li>For example one type may react with the media and turn blue while another type may appear purple </li></ul>
  9. 9. Differential Example <ul><li>To the right is a photograph of different bacterium grown on differential media </li></ul><ul><li>E. coli - blue </li></ul><ul><li>E. aerogenes - purple </li></ul><ul><li>P.aeruginosa - yellow </li></ul>
  10. 10. Limiting Microbial Growth Physically <ul><li>Microbial growth can be limited by altering one or all of the following to a level that the organism will not thrive in; </li></ul><ul><li>Temperature </li></ul><ul><li>pH </li></ul><ul><li>Gaseous Atmosphere </li></ul><ul><li>Osmotic Pressure </li></ul>
  11. 11. Temperature <ul><li>Psychrophiles – organisms that grow best between 15C – 20C </li></ul><ul><li>Mesophiles – organisms that grow best between 25C – 40C </li></ul><ul><li>Thermophiles – organisms that grow best between 25C – 40C </li></ul>Above - Microorganisms can be classified based on the temperature at which they thrive
  12. 12. Gaseous Atmosphere <ul><li>Aerobic – Typically require oxygen at levels of 21% </li></ul><ul><li>Anaerobic – Don’t require oxygen </li></ul><ul><li>Faculative – Can grow both aerobically and anaerobically </li></ul><ul><li>Microaerophilic – Typically require oxygen at levels of 1 – 15% </li></ul>Above - Classification of microorganisms based on gaseous oxygen levels at which the microorganism can grow.
  13. 13. Limiting Microbial Growth Chemically <ul><li>Adding antimicrobial agents to media will inhibit the growth of specific organisms. </li></ul><ul><li>Example - Media to which Colistin and Nalidixic acid have been added will inhibit gram-negative bacteria growth but promote Gram-positive cocci growth. </li></ul>
  14. 14. Iodine <ul><li>Kills bacteria and endospores on human skin </li></ul><ul><li>Presence of organic material decreases effectiveness of iodine to kill endospores </li></ul><ul><li>Eliminate organic material to increase rate at which iodine will kill endospores </li></ul><ul><li>Mode of action: Damages metabolic compounds </li></ul>
  15. 15. Formaldehyde Gas <ul><li>Kills bacteria and endospores in enclosed areas </li></ul><ul><li>Kills vegetative cells quicker </li></ul><ul><li>To be effective temperature must be 22 °C </li></ul><ul><li>Humidity needs to be approximately 60-80% </li></ul><ul><li>Mode of action: Inactivates nucleic acids and proteins. </li></ul>
  16. 16. Phenolic Compounds <ul><li>Bacteriostatic (Inhibits growth but does not kill) at low concentrations </li></ul><ul><li>Bactericidal (Kills) at higher concentrations </li></ul><ul><li>Mode of action: Damages Cytoplasmic Membrane </li></ul>
  17. 17. Antibiotic Mode of Action <ul><li>Can work by affecting the Peptidoglycan in the Cell Wall </li></ul><ul><li>Inhibits crosslinks from forming in Peptidoglycan </li></ul><ul><li>Peptidoglycan loses rigidity </li></ul><ul><li>Causing cell to absorb water </li></ul><ul><li>Cell splits and dies </li></ul><ul><li>Penicillins and Cephalosporins - antibiotics that work by targeting the Cell Wall </li></ul>
  18. 18. Antibiotic mode of action <ul><li>Some antibiotics kill pathogens by affecting the Cytoplasmic Membrane </li></ul><ul><li>Alters the permeability of Phospholipids in the Cytoplasmic Membrane </li></ul><ul><li>Causes leaking of vital substances from the cell resulting in death </li></ul><ul><li>Polymyxins – antibiotics that work by targeting the Cytoplasmic Membrane </li></ul>
  19. 19. Limiting Antibiotic Effectiveness <ul><li>Mutant cells that are non-responsive to the antibiotic. </li></ul><ul><li>Wrong type of antibiotic used for the specific pathogen. </li></ul><ul><li>Cells passing on antibiotic resistance to other cells through genes. </li></ul><ul><li>Increased use of antibiotics increases the risk of antibiotic resistant pathogens forming. </li></ul>

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