Microbial Populations

I.  Intra-population Interactions
  A.  Allee's Principle (Allee et al.  1949.  Principals of Animal Ecology.  Saunders, Philadelphia.)
          1.  Both positive and negative interactions may occur even withing a single population
          2.  Generally, positive interactions increase the rate of population growth to some asymptotic 
               limit, whereas negative interactions have the opposite effect and decrease growth rate to 
               some lower limit as the population density increases.
     B.  Positive interactions
         1.  cooperation
              a. metabolite leakage and uptake
              b.  colony formation (swarming in Dictyostelium)
              c.  enzyme production
              d.  genetic exchange (resistance to antibiotics and heavy metals)
     C.  Negative interactions
         1.  competition
               a.  competition for resources 
                    - prey
                    - host cells
                    - space
               b. interference competion
                    - accumulation of metabolic byproducts

II.  Growth
  A.  Growth of free cells (in culture)
     B.  Attachment
          1.  biofilm growth
           2.  algal mats
     C.  Measurement of Population Growth and Activity
          1.  Heterotrophs
               a.  Population Growth
                    - Frequency of Dividing cells (Hagstrom et al. 1979)
                    - Thymidine incorporation into DNA
                    - Leucine incorporation into protein
               b.  Indicators of population activity
                    - Heterotrophic potential
     2.  Autotrophs
          a.  Oxygen production
          b.  Changes in pH
          c.  14C-Bicarbonate incorporation

III.  Physiologicial Ecology
  A.  Factors controlling growth (nutrition, temperature, pH, oxygen)
     B.  Quiesent microbes

IV.  Starvation

V.  Mortality

VI.  Dispersal
  A.  Airborne (spores)
     B.  Waterborne (cysts)

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