Microbial Ecology Exam 1 1 
Ross Cambe
3. Molecular microbial ecology and stable isotopes. 14C and C13 Dating- gives us an idea for life, when life began and what environment looked like Radioactive- determines how OLD the material is in the environment Stable- Biological ORIGIN of material in environment Based on the concept that during life, every living thing accumulates certain amount of 14C Helps us date organisms or discoveries Biogenic origin vs. abiotic origin: 13C. fixed proportion of C12 to 13C Preferential incorporation of 12 CO2 than 13 CO2 whether the bond is easier to break or active site more active than it needs to be- incorporates 12C more 16s rRNA: 1977 Carl Woese Carl Woese used phylogenetic taxonomy of 16s ribosomal RNA to begin to define Archaea as a separate domain of life from eukaryotes and bacteria. It is important to note that though Woese defined the archaea in 1977 they would not be accepted as a separate domain of life from bacteria until the mid 80s. Importance of 16srRNA:
1. Universally distributed
2. Functionally homologous
3. Sequences are conserved
4. Molecule should reflect evolutionary change in organism as a whole
Although cannot differentiate between strains. Good starting point to differentiate between genus, DNA-DNA hybridization is alternative for differentiation between strains
4+7. Fossils- Use 14C dating Stromatolites- “microbial mats” fossilized MM gives us record of life on earth “laminated sedimentary structures formed by trapping + binding +/or precipitation of minerals by microbes” Thought of as MM in which a rock like layer of sand or precipitated minerals are present Round rock structures rarely contain fossilized microbial mats that were deposited >3 billion yrs ago Foss ilized- purple sulfur bacteria, proof of anoxygenic photosynthesis, oxidation of H2S, elemental sulfur, in rocks >3.2 billion yrs ago Contemporary- green algae, cyanobacteria, found in hypersaline lakes and high saline levels ex. Shark Bay
3. Molecular microbial ecology and stable isotopes. 14C and C13 Dating- gives us an idea for life, when life began and what environment looked like Radioactive- determines how OLD the material is in the environment Stable- Biological ORIGIN of material in environment Based on the concept that during life, every living thing accumulates certain amount of 14C Helps us date organisms or discoveries Biogenic origin vs. abiotic origin: 13C. fixed proportion of C12 to 13C Preferential incorporation of 12 CO2 than 13 CO2 whether the bond is easier to break or active site more active than it needs to be- incorporates 12C more 16s rRNA: 1977 Carl Woese Carl Woese used phylogenetic taxonomy of 16s ribosomal RNA to begin to define Archaea as a separate domain of life from eukaryotes and bacteria. It is important to note that though Woese defined the archaea in 1977 they would not be accepted as a separate domain of life from bacteria until the mid 80s. Importance of 16srRNA:
1. Universally distributed
2. Functionally homologous
3. Sequences are conserved
4. Molecule should reflect evolutionary change in organism as a whole
Although cannot differentiate between strains. Good starting point to differentiate between genus, DNA-DNA hybridization is alternative for differentiation between strains
4+7. Fossils- Use 14C dating Stromatolites- “microbial mats” fossilized MM gives us record of life on earth “laminated sedimentary structures formed by trapping + binding +/or precipitation of minerals by microbes” Thought of as MM in which a rock like layer of sand or precipitated minerals are present Round rock structures rarely contain fossilized microbial mats that were deposited >3 billion yrs ago Foss ilized- purple sulfur bacteria, proof of anoxygenic photosynthesis, oxidation of H2S, elemental sulfur, in rocks >3.2 billion yrs ago Contemporary- green algae, cyanobacteria, found in hypersaline lakes and high saline levels ex. Shark Bay