Lecture 20: Microbial Systematics and Diversity Flashcards
What is the era of heavy bombardment?
First 500 Million Years of Earth
No Evidence of Life
- Temperatures Too High
- Intense UV Radiation
- Collisions With Asteroids/Rocks
Water On Earth
-Collisions With Icy Comets
How did the formation of a hospitable earth occur?
End of era of heavy bombardment cause temp decrease
Geological and Ocean Development
What is the subsurface hypothesis for the origin of life?
First life evolved in hydrothermal vents
- warm water w/ lots of nutrients
- No UV radiation
- stable temperature
What is the early evidence of cellular life?
Stromatolites
- Layered Mixtures of Microbes – “Microbial Mats”
- Trap Mineral Materials – Fossilize
Microbial Fossils
-“Microfossils”
Microbial Forms Preserved In Ancient Rock
How long ago did microbial life first appear? What conditions were compatible w/ life?
At least 3.5 Billion years ago
Conditions
- Liquid water
- Temp (0-100 degrees)
- Anoxic atmosphere
What were the early types of microbial metabolism?
Anaerobic and Autotrophic b/c
- anoxic ocean and atmosphere
- mostly inorganic chemicals present
What were the early metabolism types that used light energy?
Phototrophy (Anoxygenic)
- Energy Source = Sun
- Electron Donor = Hydrogen Sulfide (H2S)
- Carbon Source = CO2
Phototrophy (Oxygenic)
- Energy Source = Sun
- Electron Donor = Water (H2O)
- Carbon Source = CO2
What is the chemical reactions for oxygenic and anoxygenic phototrophy?
Phototrophy (Anoxygenic)
Inorganic Carbon + H2S + Light -> Organic Carbon +
Elemental Sulfur
Phototrophy (Oxygenic)
Inorganic Carbon + H2O + Light -> Organic Carbon +
Oxygen (O2)
What is the great oxidation event?
2.5 billion years ago where atmosphere gets O2
Aerobic Respiration Possible
-Major Pathway of Most Life On Earth Today
Formation of the Ozone (O3) Layer
-Barrier to Ultraviolet Radiation from the Sun
What took so long for the great oxidation event to occur?
Cyanobacteria Produced Oxygen For 500 Million Years Before Change In Atmosphere
- Oxygen Consumed By Iron Minerals in the Ocean
- Iron Oxidation: Ferrous (Fe2+) -> Ferric (Fe3+)
How is endosymbiosis significant to eukaryotes and plants?
Free living bacteria made their way into eukaryotes/plants
Chloroplast = cyanobacteria Mitochondria = proteobacteria
What are the characteristics of mitochondria and chloroplasts?
- Contain Their Own DNA
- Have Circular DNA (like prokaryotes)
- Have Small Ribosomes (70S) (like prokaryotes)
How do mitochondria and chloroplasts produce energy?
Mitochondria -> Consume O2 -> Energy
Chloroplast -> Produce O2 -> Energy from Sun
What are the unifying features of domain archaea?
Traits Shared by All Archaea
- Ether-‐Linked Lipids
- Lack of Peptidoglycan
- Complex RNA Polymerases
What traits are only found in domain archea?
Methanogenesis
-Conserving energy from the production of methane
Life in Extreme Heat
-Only organisms in environments >100˚C
What kinds of habitats are archaea found in?
Extreme cold or heat
-antarctic sea ice, volcanic hot springs, hydrothermal vents
Extreme salinity
-Salt lakes and salterns
What are the only gram-positive bacteria?
Actinobacteria, Firmicutes, and Mollicutes
How many culture strains and uncultured strains of bacteria?
Culture Strains ~18 phyla
Uncultured Strains >80 phyla
What are the ancient bacterial phyla that are hyperthermophiles?
Aquificae
- Most Heat Tolerant (95°C)
- Aerobic Hyperthermophile
Thermotoga
- Anaerobic Hyperthermophile
- 20% of Genes from Archaea
Thermodesulfobacterium
-Ether-‐Linkage Lipids
What is Deinococcus-Thermus?
Genus Thermus
-T. aquaticus -> Taq Enzyme
Genus Deinococcus
- D. radiodurans
- Soil and Dust Particles
- Survives Intense Radiation (15,000 grays; 10 kills humans)
- Resistant to Mutagenic Compounds
What are Deinococcus radiodurans used for?
DNA Repair Enzymes
- Single or Double-‐Stranded Breaks
- Repair Misincorporated Bases
DNA Arrangement
- Cells Always in Pairs
- DNA Stored in Nucleoids
- Repair By Nucleoid Fusion
What are spirochetes?
Motile, Tightly-‐Coiled Bacteria
- Rare Example of Morphology Predicting Phylogeny
- Common in Aquatic Habitats and Animal Hosts
Contain Endoflagella
- Remain in Periplasm of the Cell
- Rotation Provides Torque Motility
What kinds of spirochetes are pathogens?
Treponema allidum = Syphilis
Borrelia burgdorferi = Lyme Disease
What is the Genus Bacteriodetes?
Common in Intestinal Tract of Animals
- Most Common Species in Human Gut
- Break Down Polysaccharides (plant matter)
