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
