1. Microbial Nutrition and Growth Nutrition = Obtaining Required Substances from the Environment

2. Essential Nutrients Must be Provided for an Organism to Survive and Reproduce

3. Nutrients Inorganic nutrients– atoms, ions or molecules that contains a combination of atoms other than carbon and hydrogen –metals and their salts (magnesium sulfate, ferric nitrate, sodium phosphate), gases (oxygen, carbon dioxide) and water Organic nutrients- contain carbon bonded to hydrogen and are usually the products of living things –methane (CH 4 ), carbohydrates, lipids, proteins, and nucleic acids

4. Macronutrients Required in Large Quantities Play principle roles in cell structure and metabolism Proteins (source of amino acids) Carbohydrates

5. Micronutrients Needed in Small Amounts – like Minerals

6. Points about Bacterial Cytoplasm Mostly water Large proportion of protein 97% of dry weight is organic matter 96% of bacterial cell is composed of C, H, N, O, P and S

7. Challenge for Bacteria How to get enough nutrients in forms that they can use to make cell components

8. Bacteria Must Make Proteins Carbohydrates Lipids Nucleic Acids

9. Sources of Essential Nutrients Carbon – obtain in organic form, or reduce CO 2 Nitrogen – Fix N 2 or obtain as NO 3 -- NO 2 -, or NH 3 Oxygen – Atmospheric or dissolved in water Hydrogen – Minerals, water, organic compounds

10. Nutrient Sources - Continued Phosphorous – Mineral deposits Sulfur – Minerals, H 2 S Metal Ions - Minerals

11. Mineral Nutrients Important in Microbial Metabolism Potassium – essential to protein synthesis and membrane function Sodium – used in some types of cell transport Calcium – cell wall and endospore stabilizer Magnesium – component of chlorophyll; membrane and ribosome stabilizer Iron – component of proteins of cellular respiration Zinc, copper, nickel, manganese, etc.

12. Growth Factors Organic compounds that cannot be synthesized by an organism & must be provided as a nutrient –essential amino acids, vitamins

13. Nutritional Types Autotrophs - use CO 2, an inorganic gas as carbon source Heterotrophs - obtain carbon in an organic form made by other living organisms

14. Autotrophs – “Self-Feeding” Phototrophs use light energy to reduce carbon or make ATP Chemotrophs use energy stored in inorganic chemical bonds to reduce carbon or make ATP

15. Heterotrophs Obtain reduced carbon compounds made by another organism Chemoheterotrophs – oxidize reduced carbon to make ATP

16. Two Kinds of Bacterial Heterotrophs Saprobes – Obtain nutrients from dead, decaying matter Parasites – Feed off a host organism

17. Environmental Influences on Microbial Growth Temperature Oxygen requirements pH Barometric pressure

18. 3 Cardinal Temperatures Minimum temperature Maximum temperature Optimum temperature

19. 3 Temperature Adaptation Groups 1.Psychrophiles – optimum temperature below 15 o C, capable of growth at 0 o C 2.Mesophiles – optimum temperature 20 o -40 o C, most human pathogens 3.Thermophiles – optimum temperature greater than 45 o C

20. Ecological Groups by Temperature of Adaptation

21. Oxygen in the Microbial Environment Oxygen required by aerobic species (Bacillus, Pseudomonas) but produces toxic by-products; these species have efficient de-tox enzymes Facultative anaerobes can exist in presence of oxygen but have no requirement for it (E. coli, Staphylococcus, etc.)

22. Anaerobes – no Need for Oxygen Strict anaerobes cannot tolerate oxygen (Clostridium sp.) Aerotolerant anaerobes have atypical oxygen detox systems (Lactobacillus sp.) Capnophiles require higher CO 2 pressures (Neisseria, Brucella, S. pneumoniae)

23. pH Effects on Growth Acidophiles require low pH (Thermoplasma) Alkalinophiles require high pH (Proteus)

24. Osmotic Effects Most microbes exist under hypotonic or isotonic conditions Halophiles – require a high concentration of salt Osmotolerant – do not require high concentration of solute but can tolerate it when it occurs

25. Miscellaneous Environmental Factors Barophiles require high environmental pressure (like deep sea Archae) Dehydrated Cell Stages – Spores Extreme radiation conditions - Dinococcus radiodurans

26. Ecological Relationships Symbiosis – existing together Mutualism – both parties benefit Commensalism – one party benefits without impacting the other Parasitism – one party benefits at expense of the other Synergism – multiple organisms working together

27. Microbial Biofilms Biofilms result when organisms attach to a substrate by some form of extracellular matrix that binds them together in complex organized layers Dominate the structure of most natural environments on earth Microorganisms communicate and cooperate in the formation and function of biofilms – quorum sensing

29. Ecological Relationships - Continued Antagonism – one party acts to inhibit or eliminate the other Example of antagonism: Antibiosis – producing substances toxic to other organisms

30. Microbial Growth Growth of a population at an exponential rate under optimal conditions

31. Stages in Normal Growth Lag phase Exponential/log phase Stationary phase Death or decline

32. Mathematics of Population Growth

33. Growth Curve

34. Methods for Monitoring Growth Dilution Plating Turbidity analysis using spectrophotometer Direct count with hemacytometer Optical detection – Coulter Counter

35. Turbidity

36. Direct Microscopic Count

37. Electronic Counting

38. It is Ideal to Perform Most Manipulations of a Culture When it is Growing in Log Phase