gut biome Flashcards
what is a microbiome
an assembly of microorganisms their genes and gene products and the surrounding environmental conditions
An integrated approach looking at
- who is there?
- what can they do?
- what are they doing?
what is meant by the term holobiont
a biological concept which refers to a host organism and its associated symbiotic microorganisms as a single ecological unit, emphasising the idea that an organism is not just an individual but rather a community of the host and associated microorganisms
where are animal microbiomes
any where which is hospitable for a microbe to live, areas of the body have different conditinos such as PH which is suitable for different organisms so microorganism diversity differs in diffent parts of the body
most common areas = hairs, nostrils, skin, oral cavities
how does the microbiome affect physiology
- digestion, nutrient uptake and metabolism e.g. fermentation in herbivores for cellulose breakdown and absorption
- immune system
= provides initial training for immune systems as well as acting as a form of protection by colonisation resistance preventing pathogens becoming established - brain and behaviour
- endocrine and cardiovascular system
what is considered a healthy microbiome
one which is dynamic and plastic= able to rapidly change and respond to fluctuations in the environment due to selective pressures in the host differing depending on type of host resulting in different types of microorganisms such as affect of diet and environment
what is the most common way to investigate the way microbiomes affect physiology
Gnotobiotic and axenic models
1) axenic = taking all microbes out of a system
2) Gnotobiotic = taking a known concentration of microbes and putting it into an axenic system to investigate affects
what is meant by the term dysbiosis
the animal-microbiome relationship is finely balances and disruption to this system is known as dysbiosis which can result from diet and stress causing impacts on health and fitness, increasing disease susceptibility e.g. leaky gut syndrome
dbyotic state = disruption in the relationship causing reduced beneficial microbes and increased bad ones
outline microbes in the digestion of insects
foregut = storage of digested food
midgut = same as stomach in
vertebrates, majority of digestion and absorption
hindgut= same as large intestine, majority of fermentation, more developed with more bacteria as they eat plants
outline how termites have a specialist lignocellulose degradation system in their digestion
- they eat wood
- strong manacles to physically break it apart along with a pronounced gizzard with muscular ridges
- particles combine with saliva and enter the midgut where the majority of glucose absorption occurs
- lignose cellular material remains and is broken down and nutrients relaced in the hindgut due to the large number of communities present which release enzymes to break down cellulose and release nutrients in short tail fatty acids
outline how microbiomes in humans aid in digestion and absorption
communities are present in different regions of the gut due to difference in conditions
stomach = acidic so not favourable to many individuals
small intestine = increased number of microbes present
large intestine= most number of microbes (more than a trillion) with distinct communities either associated with the mucus or the lumen where fermentations occurs releasing short chain fatty acids
how is the house mouse digestion system and microbiome adapted to the species
mouth, oesophagus and stomach differ in composition compared to small intestine
omnivore but eat a lot of plants so have a large cecum and colon which is involved with fermentation
how are ruminants digestive and microbiome systems adapted to their diet
- highly evolved symbiosis with an abundant and diverse community of bacteria, fungi, archaea, protozoa and phages
- fermentation results in production of hydrogen and co2 which form methane which is produced by the arache in the rumen
how have some species developed adaptive microbiomes to suit their diet of hard to digest foods
some microbiota allow the metabolism of dietary toxins known as secondary metabolites for example koalas which eat eucalyptus which is hard to break down and produces toxins
- slow metabolism increases time for digestion and absorption
- extended cecum increases fermentation in large intestine
- microbiomes breakdown cellulose and toxins inhibiting toxic effects
how can understanding the adaptive microbiomes of some species be used in a conservation setting
microbiome transplants can be completes allowing the enhancement of dietary ranges in species for example some species of kolas eat different types of eucalyptus
by transplanting the microbiome of one species into another it allows them to eat that type of eucalyptus species as well
outline some examples of species whose microbiomes allow them to eat foods which produce secondary metabolites (toxins)
1) Desert woodrats= shrubs with a toxic coating, proved by experiment which removed rat microbiome with antibiotics resulted in them feeling the toxic affects
2) Daphnia microbiomes allow them to improve to toxic compounds in the water such as seen in cyanobacterial blooms
3) Earthworm microbiomes breakdown and sequester heavy metals seen in the soil
how can microbiomes enhance the ability to exploit new niches
allows individuals to eat a range of foods (generalists) allowing them to exploit bigger home ranges and provide direct energetic advantages in contrast to specialist individuals
invasive species can be successful if they have flexible microbiomes allowing them to utilise different environments such as signal cray fish which give adaptive advantage
how have microbiomes been show to increase cold tolerance in some species
experiment acclimated mice to cold conditions and saw both the mice and microbiome became tolernant fo the cold
- they transplanted microbiomes from cold population with contol and vise verse
- tested cold tolerance and found control mice now had increased cold tolerance and cold acclimated had decreased
REASON= cold tolerant microbes promoted the incidence of brown adipose tissue which generates more heat increasing thermogenesis as well as increasing uptake of glucose and increasing sensitivity to insulin
how have microbiomes been show to increase thermotolerance in corals and how can it be used for conservation
found some corals with higher tolerance for warming oceans had specific bacterial colonies present
by transplanting these colonies to other coral systems we can increase heat tolerance and potential aid coral reefs with warming oceans
how can microbiome engineering be used to reduce methane production
problem as it contributes to 25% of human methane production and causes a loss of energy for the species as it converts and forms methane
- inhibit methogenesis by feeding additives to get ride of methogens within the tumen using
1) 3- Nitrooxypropanol = inactivated archaeal methyl-coenzyme M reductase
2) Red seaweed = bromoform inhibits methyl transfer
how can microbiome conditions affect early life microbiomes of farmed fish
microbiome is highly plastic and dynamic in early life
the egg shell has microbes associated with the outside which enter when fish hatch and early colonisers are important on impacting how the animal microbiome will be
stressors in aquaculture such as bleaching eggs to prevent pathogen had negative impacts on microbiomes
by integrating sensitive conditions effects we can promote good probiotic bacteria which have good effects on animal health and welfare
name some key probiotic taxa present in the large intestine of mammals
Mucosal layer
1) enterococcaecae
2) lactobacillaceae
lumen
3) Enterobacteriacaeae
4)lactobacillaecaea
5) streoptococcaceae
