positive bioassociations of microbes Flashcards
what are the two types of symbiote transmission
vertical transmission
horizontal transmission
(can be mixed)
how does symbiosis develop
through the prolonged association and coevolution between two partners
phylosymbiosis def
a microbial community that recapitulates the phylogeny of the host
what happens to the genome of a microorganism in symbiosis with a higher organism
the genome shrinks as the microbe can get plenty of biomolecules from its host, so it won’t need to synthesise them for itself.
why is a smaller genome more beneficial
a smaller genome requires less resources and energy to replicate.
how to symbiotes attach to their hosts
they could insert effector proteins to allow the microbe entry.
Once inside the host the microbe will secrete biomolecules to prevent the hosts immune system from attacking it
How is the Hawaiian bobtail squid an example of symbiosis
-symbiosis with A.fisceri
-bioluminescent bacteria desguises the squid as moonlight from above or below
-transmission is horizontal since the squid isn’t born with the bacteria
-the light organ of the squid is specifically colonised within 6 hours
what is Quorum sensing
a method of cell to cell communication used to coordinate gene expression and communal behaviour
widely employed
achieved by the release and detection of autoinducers
a larger colony means a greater concentration of autoinducers allowing the colony to sense how large it is
what can quorum sensing control
sporulation
bioluminescence
virulence
biofilm formation
how are marine sponges an example of symbiosis
vertical transmission from parents
can be very dependant or very independent from microbes.
the microbes metabolise nitrogen and essential vitamins
some microbes produce compounds that deter predators
the bacteria eat organics from water whilst the sponge then eats the bacteria
what is wolbachia
a group of symbiotic bacteria that is incredibly widespread in insects
vertical transmission
manipulates host reproduction, infected females are favoured over uninfected ones
how is wolbachia used to control mosquitoes
when infected males mate with uninfected females they produce unviable offspring.
This can be used in lab raised bacteria to outcompete and eliminate wild populations that may carry disease
what are the characteristics of the rumen
anaerobic
contains microbes that break down plant fibre
produces strong greenhouse gasses like methane
what is the composition of the rumen microbiome
composed of bacteria, protists, archea and fungi
what are Fermicutes and Bacteriodetes
the cellulose degrading bacteria found in the rumen
what is luciferin and luciferase
luciferin is a molecule that reacts with oxygen to create light. this is seen in most bioluminescent organisms. This reaction is catalysed by luciferase.
What is a luciferase assay
we can use luciferase as a reporter gene and add the gene that codes for luciferase into the genome, before other genes we want to study.
we can then measure gene expression by the amount of light produced
Explain the anaerobic food web that takes place in the rumen
-a few bacterial species break down plant fibre and turn it into sugars
-other bacteria can then ferment the sugars into volatile fatty acids
-finally methanogenic bacteria turn H2 along with specific fermentation products into methane
what are VFAs
Volatile Fatty Acids. These are used as a food source for the rumen mammal.
VFAs make up 70% of the animals cellular energy requirement
what are the 3 main groups of microbes in the human gut
Bacteriodetes
Firmicutes
Proteobacteria
explain the gut brain axis
The idea that the host can influence its microbes and vice versa. The host and microbes communicate through metabolites, hormones and neurotransmitters
what are the main benefits of microbes for plants
-nitrogen fixation
-converting essential elements into forms plants can access
-producing plant hormones like auxins
-protect against pathogens
what are nitrogenases
enzymes found in rhizobia bacteria found in the root nodules of legumes. They convert N2 to NH3 in microaerophilic environments (low oxygen).