Lecutre 29 Flashcards
What is microbial ecology?
- how bacteria interacts with the environment (TALKING)
Natural environments - the unseen majority - how do we know 20 - 50% of earths biomass is made up of prokaryotes
Prokaryotes make up 20-50% of the earths biomass
- most organisms cannot be or have not been isolated in pure culture
- identification is now done using genetic fingerprints - very specific and unique ((this is done using the 16s rRNA gene (it has been conserved over billions years of evolution - universal component for protein synthesis across all 3 kingdoms) and bacterial classification - phylogenetic signatures contained in nucleotide base sequences which can be used to characterise every single organism))
- currently there are millions of unique 16s rRNA sequences (molecular barcode) available in database
- the majority of these genes are therefore from uncultivated bacteria
The ______ microbial world is far greater then the _______ world
The uncultured microbial world is far greater then the cultured world
(We have a good pricture of the microbial world through phylogenetic signatures, metagenomics)
Individual microbial cells of a species proliferate to form a ….
Population
Populations interact/communicate to form ….
Communities
What is microbial ecology?
The study of the interrelationships among microorganisms and their environment
Molecular tools gave rise to the term MICROBIOME
What is a microbiome
- all the micro organsims and their genes within a particular environment
Enrichment culture (not core)
- providing the temperature and chemical conditions in the laboratory that encourage the growth of specific microbes
Mesocosm =
An experimental system that stimulates real-life conditions as closely as possible
One process (breakdown of substrate) —-> two potential goals
- harvest energy
- harvesting of building blocks
This process can run in reverse - you would then need both energy (to create the bond) and a building block (to attach that bond)
Reduction - oxidation in bacteria
- the basis of energy transfer in cells
- for every action (e.g oxidation) there is an equal and opposite reaction (reduction) - coupled
- energy harvested from the environment is converted to a ‘local currency’ inside the cell
- NADPH and NADH serve as intermediates to transfer energy inside of cell
- NAD+ and NADH facilitate redox reactions without being consumes - they are recycled (levels stay the same)
A redox reaction is…
Shuttles through NADH/NADPH
Primary produces vs decomposers
Carbon —-> macromolecules (+energy) ——> cells
Autotrophs (primary producers)
- fix CO2
- self sufficient, do not require carbon
Heterotrophs
- decomposers
- need fixed carbon, cannot use CO2 directly
- dependent on primary producers
Two energy sources
+Chemo = chemical: organic or inorganic compound (electron donor)
- organic e.g glucose
- inorganic e.g H2S
+ Photo = energy from sunlight
Chemotrophs = use chemical energy from either
- C compounds = organic
- Non C compounds = inorganic
Phototrophs = use solar energy
All chemo autotrophs use…
Inorganic compounds
Photoheterotrphs (plants ) use..
.. organic carbon not CO2
Tropic groups (funky diagram)
How can so many different microbes share the same metabolisms and live in the same environment exploiting the same source
EG microbial mat in a marsh - layers of different coloured microbes.
- photosynthetic pigments have complementary absorbtion spectra
- light = common resource
- avoid completion by tuning their antenna to different wave length
- (they aren’t actually competing because they’ve been programmed to catch different parts of the spectrum)
Oxygen dependent organisms living in anoxic environments (NOT CORE SLIDE)
- bacteria live in anoxic environments
- but create cables to shuttle electrons from anoxic into oxidation zones
- allows them to breathe oxygen while living in anoxic conditions
Take home…
- all organisms need to eat (gather energy)
- if life is present, energy is being harvested from something
- if one source of energy is missing, there must be another one to sustain life. Find it and all the communities redox profile will match it
