Atmospheric Habitat
regions in atmosphere
troposphere
nearest to earth
characteristic
ait temperature
atm pressure
concentration oxygen
organic Carbon
water radiation
most highly populated area among region
from surface to about 10km
temperature at upper levels reach -43 to -83
upper levels too extreme to support life
location of the 'bad' ozone
stratosphere
increasing temperature with height --> -10km to 45km
location of good ozone, limits UV light
extreme low temperature
lacking liquid water
mesosphere
temperature decreasing with height
thermosphere
temperature increases with altitude
exosphere
extending into outer space
Helium and Hydrogen predominant
ionosphere
45km to 100km
extreme UV and ionizing radiation levels
sopres better adapted to atmospheric
have low mwtabolic rates
are produced in high numbers
thick cell walls --> against dessication
some are pigmented --> protection against UV radiation
small size and low density --> airborne
xenospores
forms that are primarily adapted to reproduction vs. resistant to environmental stress
fungi
algae
protozoans
bacteria
eg. actinomycetes
xenospores vs. endospores
xenospores form on or in specialized structures
endospores forms within the vegetative cells
xenospores represents an adaption for fecundity
one cell --> many spores --> survival rate low
endospores represents an adaption for survival
one cell --> one spores --> survival rate high
other extreme environments
with severe conditions
high or low temperature
pH
irradiation
toxic chemicals
lack of nutrients, water availability
ionizing radiation
hot springs
at volcanic areas
grows of microorganism limited by
high temperature
high acidity or alkalinity
low concentration of organic matter
Subtopic
predominant bacterium: Bacillus stearothermophilus
acid springs and lakes
pH 3 or less
Ferroplasma acidarmanus
pH 2.0
capable of massive surface growth in flowing waters in the subsurface
posesses a single peripheral cytoplasmic membrane
no cell wall
salt lakes
high concentration of sodium chloride
high salt causes
dehydration
precipitation of intracellular proteins
predominant bacteria: Halobacterium
adaption feature
cell structure and enzyme naturally require stabilization from sodium
require a sodium ion of min [1.5M], OPTIMUM [3-4M]
antartica
environmental condition
low temperature
low humidity
high velocity of desiccating winds
high radiation
food web --> 3-4 levels of species
community diversity is low
dispersal of airborne particles
3 stages
a) liberation and take-off into the air
requies energy to overcome adhesive forces and still air layer
features of adaption for airborne dispersal
virus and bacteria are poorly adapted
fungi have many adaption features
eg tall sporophores ; forceful ways to projects spores into air
(b)dispersion in air currents
depend on physical characteristic of particle (eg spore) and the atmosphere
spore
size
shape
degree of surface roughness
density
environment
wind movements
turbulence
air humidity
convection (changes of air due to the temperature)
(c)deposition
methods
sedimentation due to the gravity
impaction wioth surfaces
brownian movements
electrostatic deposition
rainwashing
physical features of the aerial environment
air movements in the troposphere
main agent of dispersal
kinetic energy for movements of air --> provided by solar energy
principle
temperature decreases with altitude
sun heats up the ground, create gradient
displacement pf air occur
radiation
radiation from the sun
mostly absorbed or reflected back but most microorganism at higher region of troposphere may be exposed to damaging doses
precipitation
water vapour --> continually recycled
average time of water vapour in air = about 9 days
endosopres
forms that are primarily adapted to resistance rather than reproduction
limited to gram-positive bacteria
Subtopic
xenospores and endospores
both are more resistant than parental cells
very low metabolic rates (low maintenance energy)
thick cell walls protects again dessication
pigmentation protects against UV light and photooxidation
many high surface area: weight ratios
survival in air dried states
biomass in the atmosphere (surface to 3km)