Lecture 40: Colourful Microbes Flashcards
By sequencing DNA you can…
- Tell what organisms are there
The majority of genes are from uncultivated bacteria, the uncultured microbial world is far greater than the ______ world.
- Cultured
The human colon has about ___ trillion bacteria. Individual microbial cells of a species interact to form a population. There are ____ of microbes, think of as a ______ community. Something that could affect this natural microflora include ____-_____ ______. There are bad guys and guys, need to _____ down.
- 20
- Heaps
- Stable
- Wide-spectrum antibiotics
- Narrow
Sergei Winogradsky (Microbial Ecologist):
- Found that the environment his bacteria lived in smelled like rotten eggs (hydrogen sulfide)
- Really wanted to work with it in his lab
- In order to do this you need to figure out how to grow the bacteria (enrichment culture)
- Bacterium transformed an inorganic molecule to get energy
- Could fix CO2 like plants
Enrichment culture:
- Providing environment that mimics real environment microbes usually live in to promote growth
Mesocosm:
- An experimental system that simulates real-life conditions as closely as possible
- (What might be happening in a lake, estuary, etc)
Winogradsky Column:
- Perpetual life in a tube (keeps living on and on)
- “Feeds” off itself
Bacteria need three things to grow:
- Carbon Source
- Energy Source
- Reducing power
Chemo =
Photo =
- Chemical: organic or inorganic electron donor
- Photo: Energy from sunlight
Humans are ______trophs.
- Chemoheterotrophs
How do trophic groups lead to the formation of a microbial community?
- Colours come from activity of photosynthetic bacteria
Winogradsky Column layers:
- Water
- Sediment + calcium carbonate + calcium sulphate + paper (cellulose)
- You end up getting a vertical stratification
- MAKE SURE YOU STICK IT IN THE LIGHT
“Life in a Gradient”
- Gradient of oxygen, lots of oxygen at the top, none at the bottom
- Two groups of bacteria then: aerobic bacteria at the top, and anaerobic bacteria at the bottom
- Fermentation happens when anaerobic bacteria convert cellulose to product (acids) (eg acetate)
- You end up finding bacteria growing on these end products
- Sulfate reducing bacteria
Sulfate reducing bacteria chemoheterotrophs:
- Acetate –> CO2
- If you oxidise something you have to reduce it
- Start to smell hydrogen sulfide (sign that W column is working)
DONT DUMP ORGANIC WASTE IN THE OCEAN:
- Because hydrogen sulfide will be made and FISH will DIE
Photoautotrophs in the winogradsky column:
- Use hydrogen sulfide and light
- Photosynhetic bacteria grow in the upper and middle regions (Purple and Green)
Anoxygenic photoautotrophs:
- Carry out photosynthesis anaerobically
- Green sulphur bacteria get H2S first
- Hydrogen Sulfide gradient, lots @ bottom, not much @ top
- Big sulfur granules inside cell
- HYDROGEN = ELECTRON DONOR
Oxidation-reduction reactions are _____.They go hand in hand.
- Coupled
- H2S —> S oxidation
- NADP+ –> NADPH2 reduction
- NADPH2 –> NADP+ oxidation
- ? —-> CO2
Bacteria have light harvesting pigments, what happens is that…
- An electron gets excited (or driven to a much higher electronegative potential)
- Electron never leaves the wire in cyclic phosphorylation, sending electron up the chain, then letting it fall down, using light to drive it up
- This is anoxygenic
Oxygenic photoautorophs:
- Cyanobacteria (played in a big role in putting life on this planet? Putting oxygen in air)
- Carry out photosynthesis aerobically and evolve O2
- NON-CYCLIC
All organisms are depending on light to make energy. How are they competing with each other?
- If you’re the cyanobacteria, you’re the winner right?
- You get first use of the light
- They capture different wavelengths of light!!!
- Cyanobacteria and algae use (500 - 550 nm)
- Purple = >800 nm
- Green = 550-850 nm
- NO CHOLORPLASTS IN BACTERIA
- Put photosynthetic pigments in their membranes
- This is bacterial chlorophyll
Photosynthetic pigments have complementary absorption _____.
- Spectra
Microbial ecology:
- The study of interrelationships among microorganisms and their environment
Venter:
- Sequence the human genome and the first person to make Artificial Life
