Slide 1 - Oswego by dffhrtcv3


									Microbial Ecology

      --- study of the habitats and interactions of microbes with each
              other and with more complex organisms
      --- microbes play many essential roles in most ecosystems
              primary production (photo or chemo synthesis)
              biodegradation and elemental recycling
              nitrogen fixation

      Steps in Microbiology Ecology

             1.) Identification (can be a problem with microbes!)

             2.) Determination of habitat (where does it live?)

             3.) Finding the organism’s niche (what does it do?)
First Question is Often “Who’s Out There”?

      --- Fluorescent Antibodies (Fluorescence In Situ Hybridization)
      --- 16 S rRNA, mass spec, classical, etc.

      How Many?

             --- direct count (microscopic evaluation)
             --- viable count (what can be grown in lab)

      How many of the direct count are viable?

             --- Nalidixic acid assay, causes actively
                      respiring cells to enlarge
Groups of Bacteria

      --- it has become clear that most bacteria do not normally
                live in isolation

      Consortia, groups of bacteria that live together and often
            depend upon other consortia members to provide
            some or all of their nutrients

             --- the consortia effect is probably the leading reason
                      we can grow such a relatively low number of
                      bacteria as pure culture in the lab

      Guilds, groups of bacteria that have similar nutritional and
              metabolic needs (methanogens, sulfur oxidizers, etc.)
       Chemical compounds synthesized by particular groups of
   bacteria that can act as a stand-in for cells, usually easier to detect
   than whole cells.

                --- coprastanol (a by product of bacterial cholesterol
                      metabolism) serves as a biomarker for
                      mammalian fecal matter

Indicator Species
        An easily identified species that suggests the presence of
 its consortia or group members.

                --- E. coli often serves as an indicator of fecal waste
                --- However, it is probably not as good as once thought
      --- complex three dimensional structures produced by bacteria
             (can rival the complexity of animal or plant tissue)

      --- may be made by a single species or by a consortia
      --- often composed of extensive extracellular material which
               may serve to protect the bacteria inside


             Pseudomonas aeruginosa can form an extremely hard
                   to treat biofilm on artificial joint surfaces
                   (essentially impervious to antibiotics, 10% of
                   hip replacements will require surgery within
                   3 years because of P. aeroginosa biofilms)

             Biofilms cost millions to remove from municipal water
                    systems and can harbor disease causing
                    bacteria that are protected from chlorine
                    by the biofilm

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