Nutrition

1. Nutrition Macronutrients : C,H,N,O,P,S

2. Carbon • Required for the synthesis of all organics • Carbohydrates • Lipids • Proteins • Nucleic acids •  Sources • Organic • Monosaccharides, disaccharides, polysaccharides, proteins, lipids, nucleic acids, phenols, etc. • Inorganic • CO2 and CO

3. Phosphorous • Required for the synthesis of: • Nucleic acids • Phospholipids • ATP • Sources: • Organic and inorganic • The inorganic form is the most used

4. Nitrogen • Required for the synthesis of: • Amino acids • Nucleic acids • Peptidoglycan • Sources: • Organic: amino acids • Inorganic: NH3, NO3 & N2

5. Sulfur • Required for the synthesis of: • Amino acids (Cysteine/Methionine) • Vitamins (thiamine and biotin) • Sources: • Organic: amino acids • Cysteine and methionine • Inorganic: • S, SO4

6. Hydrogen and Oxygen • Required for the synthesis of all organics! • Carbohydrates • Lipids • Proteins • Nucleic acids • Sources: • Organic: • Any organic compound • Inorganic: • H2 (Methanogens only) • H2O (Mainly autotrophs)

7. Nutritional Classification • Carbon source • Heterotrophs : • Preformed organic molecules • Autotrophs: • Inorganic molecules • CO2 and CO

8. Nutritional Classification (cont’d) • Source of energy • Phototrophs: • Light • Chemotrophs: • Oxidation of either organic or inorganic compounds • Source of e- • Organotrophs: • Reduced organic molecules • Lithotrophs: • Reduced inorganic molecules

9. Nutritional Types • Nomenclature: • Source of Carbon-Energy-Electrons • Ex. Autotroph photolithotroph • Heterotroph photoorganotroph • Autotroph chemolithotroph • Heterotroph chemoorganotroph

10. Producing Energy • Oxidative-Respiration • Aerobic • O2 used as a final e- acceptor • Anaerobic • Inorganic final e- acceptor other than O2 is used • Fermentation • Organic final e- acceptor is used

11. Microbial Energy Metabolism • Glycolytic pathways • Respiration • Fermentation • Chemolithotrophy • Photosynthesis

12. Glycolytic Pathways • Glycolysis: • Most common glycolytic pathway • Partial oxidation of glucose to pyruvate • Net production of 2 ATP • 2 NAD are reduced to NADH Each of these steps is carried out twice for each glucose molecule

13. Respiration • Features • Pyruvate is completely oxidized to CO2 • NADH is oxidized to NAD • Essential for continued operation of glycolytic pathways • Uses an inorganic electron acceptor • Aerobic respiration: O2 is the final e- acceptor • Anaerobic respiration: An inorganic substance other than O2 is the final e- acceptor • Ex. nitrate, nitrite, sulfate • Additional ATP are made

14. Aerobic respiration : Final e- acceptor: O2 3 ATP/NADH 2 ATP/FADH Anaerobic respiration: Final e- acceptor other than O2: NO3, NO2, SO4, etc. Respiration – Electron Transport Chain

15. Fermentation • Features • Pyruvate is reduced to organic acids or alcohols • Final e- acceptor is organic • NADH is oxidized to NAD: • Essential for continued operation of glycolytic pathways • O2 is not required • No additional ATP made • Gasses (CO2 and/or H2) may be released

16. Culture Media

17. Types of Media • Liquid (Broths) • Allows growth in suspension • Uniform distribution of nutrients, environmental parameters and others • Allows growth of large volumes • Solid media • Same as liquid media + solidification agent • Agar: Polysaccharide derived from an algae

18. Non inoculated clear Turbid + sediment Turbid Clear + sediment Growth in Broths

19. Single colony Growth on Agar • Growth on solid surface • Isolated growth • Allows isolation of single colonies • Allows isolation of pure cultures

20. Solid Media (Cont’d) • Slants • Growth on surface and in depth • Different availabilities of oxygen • Stab • Semi-solid medium • Long term storage • Low availability of oxygen

21. Nutritional Complexity • Nutritional complexity is a function of the biosynthetic capacity • The greater the biosynthetic capacity, the lower the nutritional requirements

22. Complex Media • Composed of rich and complex ingredients • Ex. Soya protein extracts • Milk protein extracts • Blood products • Tomato juice, etc. • Exact chemical composition is unknown • Can be selective and/or differential

23. Defined Media • Known chemical composition • Can contain up to 80 different ingredients • Can be very simple • Allows the growth of a restricted number of microorganisms • Composition is highly variable according to the microorganism • Can be selective and/or differential

24. Selective Media • Contain compounds which inhibit or kills the undesired organisms • Ex. Medium containing penicillin only allows the growth of penicillin resistant microorganisms

25. Allows to discriminate different species Often contain pH indicators Allows to discriminate different metabolisms Production of alkali changes medium to red Production of acid changes medium to yellow Differential Media

26. Environmental Parameters • Oxygen requirements • pH • Temperature • Solute concentration/Water availability

27. Oxygen Requirements • Aerobic: • Absolute requirement of oxygen for survival • Oxygen is used as a final electron acceptor • Oxygen is used by bacteria which have an oxidative metabolism or perform aerobic respiration • Microaerophilic: • Absolute requirement for low oxygen concentrations • High concentrations are deadly

28. Oxygen Requirements (cont’d) • Anaerobic/Aerotolerant: • Oxygen is tolerated but not required • Facultative anaerobes: • Facultative oxygen requirement • Can choose to use oxygen or not • Have an oxygen dependent and an oxygen independent metabolism • Strict or obligate anaerobes: • Oxygen is not used nor tolerated; cannot survive in the presence of oxygen