L10: Species Flashcards
How many bacteria exist
*one gram of soil has 1.3K
*each insect gut symbiont has 80K bacteria => millions of insect species species
What is the relationship between habitat and culturability?, what does this depend on
*microscopic counts exceed viable counts because those observed in culture cannot be grown in culture
*some may also be VBNC
all of this habitat dependent
What about habitat influences culturability
can better culture from nutrient-rich habitats, oligotrophs are hard
Most to least culturable habitats
soil => sediments => seater =>unpollutated estaurine waters => mesotrophic lakes => freshwater
Why are some bacteria non-culturable, distinguished between known and unknown species
Known species
* cells may have entered VBNC
*cultivation techniques are known but hard
Unknown species
*Cells are VBNC
*cultivation techs that would have grown were not used
*currently we cant
Complications with selecting media
*every time u select you are limiting nutrient/conditions something else, all heterotrophs should be able to grow
What can u consider for bacteria that are not currently culturable?
*complex growth factors
*complex host factors
*may be symbionts
*may be obligate intraorganism
*may grow slowly
*may not form colonies
NO: Discuss VBNC and their pathogens
*Salmonella, V. Choloera and LEgionella are well-known examples when exposed to stress conditions like osmotic sock, cold shock…
*can still infect and cause disease despite being VBNC
*revivial in host may be gentler because its hard to surivie oxidative bust from nutrient rich media
*revive gently
E. Fisheloni (characteristics)
*obligate symbiont in the gut of tropical fish, visible to make eye
*deflating zeppelin shape with 3X10^6 vell volume, and the size is constricted by diffusion barrier
NO: Techniques to discern features of VBNC
- can be identified microscopically and FISH
*physiologly can be hypothesised from appreance and ecological contexts to discern interactions
*can use micrmanipulation/isolation techniques to characterize
*can obtain genome
but at the end of the day they need to be cultured to be properly studied
E.fisheloni ecology, phylogeny and reproduction, life cycle
- never been cultured
*heteropth that lives in nutrient rich water and may help host digest food via extracellular enxymes
*phylogenitically similar to Firmicutes
*there are similar fish in herbivorous fish
Life Cycle
*circadian viviparous life cycle but some isolates don’t divide by binary fission and use modified endospores
Limits of genome sequences
do not know if the gene is expressed must use transcriptomics
Why can we not grow it
- it is a symbiont
- circardian thrytm and digests wen sleeping
- During the day it grows from two poles of the mother cells (2/mother)
- At night it forms a tough coat and hatches in the morning
How can a single copy of the genome control a large volume? What does this reveal
t does not. it makes copies of the genome that can be distributed throughout the cytoplasm
This shows extreme polyploidy
Describe temperature, oxygen and dead things availability in the ocean.
temp
* is higher at top and drops towards bottom, colder at the bottom of the ocean
oxygen
*will diffuse from the atmopshere, more light, more oxygen
* in water coloum there is minimum zone, less photosyntheiss but still a lot of nutrients so organisms are consuming it still so there is a drop
* then the oxygen will increase again
Dead things
*dead things fall to the bottom, poop from birds
*PN (dead things) will break down. ammonification will break down ammonia, be oxidised for food and NO3- is the byproduct
==> PN ⇒ NH4+ ⇒ NO2- ⇒ NO3-
* this bottom water is forced up perdiodically (upwelling) which brings the NO3 up
*brings relativley high concentrations of nitrate up and thats where it lives
