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Transcript
Environmental
Microbiology
Applied & Environmental
Microbiology
applied microbiology is the interaction of
the microbial world and the rest of the
world
– genetic variances
– microbial effect on soil, water, our
food
microorganisms are present in most
every aspect of our lives
– microorganisms are critical to our
survival on Earth
to be a successful ecosystem on Earth,
you’d best be nice to the
microorganisms!
Microbial Ecology:
relationship of microorganisms with each
other and their environment
ecosystem: interaction of living
and non-living components
– oceans, deserts, marshes,
forests, tundra, lakes
– microorganisms play a key
role in ecosystem structure
Microbial Ecology:
relationship of microorganisms with each other and
their environment
microenvironment: immediately
surrounds a microorganism
– relevant to survival and growth
of the microorganism
Nutrient Acquisition within an
Ecosystem
3 main levels exist in every ecosystem in regards to
nutrient acquisition
– producer
– consumer
– decomposer
1. primary producers:
convert CO2 to
organic material
Nutrient Acquisition within an
Ecosystem
2. consumers
– heterotrophs
– utilize organic
material created
by producers
Nutrient Acquisition within Ecosystem
3. decomposers
– heterotrophs
– digest leftovers of primary
producers and
consumers
detritus ( fresh or
partially decomposed
organic matter)
– bacteria and fungi are
key players in the
process of decomposition
Low Nutrient Environments:
common in nature
bacteria do best in biofilms if
nutrition availability is low
– biofilms are a
polysaccharide encased
community of
microorganisms
– microorganisms extract
nutrients that are absorbed
by water from air or
nutrients that are adsorbed
onto the biofilm
Microbial competition and antagonism
most environments are suitable to many kinds of
microorganisms
only one or a few can actually occupy the environment
at a given time
Competition and Antagonism:
among microorganisms
competition:
– fierce competition for nutrients and water
– the faster a microbe reproduces the larger the
population
– the larger population competes better
critical, especially if the microorganisms
competing utilize similar nutrients
antagonism
– bacteriocins: protein produced by bacteria that
destroys similar strains
“WINNER TAKES ALL AND IS KING/QUEEN OF THE
MICROBIAL ECOSYSTEM”
Example of Competition
stability of microbial community in human intestine is
attributed to competition and antagonism amongst its
members
– compete nicely for nutrients
– produce toxins to limit growth of new microbes
Environmental Change affect microbial
population
environmental fluctuations are common and resident
microorganisms may respond by
– producing enzymes to help adapt to changing
environment
additional or different enzymes may be necessary
for survival
– mutation
– domination by other species (can’t compete any
more)
Microbial Mat:
thick, dense, organized biofilm
generally found attached to a solid substrate or at airwater interfaces
Microbial mat attached to
rocks
Microbial mat in stream bed
The Study of Microbial Ecology
somewhat difficult to accomplish
– less than 1% of
environmental
microorganisms can be
successfully cultured in the
lab
Microbial Habitat
aquatic
– marine:
deep waters are usually stable and consistent
shoreline habitat varies due to nutrient rich run-off
Microbial Habitat
freshwater:
algae
– lakes
stratification allows for the mixing of the water
seasonally.
Increases the presence of O2 in the deeper H2O
paramecium
Microbial Habitat
moving water
– rivers
generally aerobic due to
turbulence facilitating O2
circulation
river ostracod
Microbial Habitat
terrestrial
– microorganisms are critical to soil habitat
composition of microbes is dependent on soil
conditions
wet soil: anaerobic conditions due to water filling
the pore space in the soil, soil dries and
microbes go produce endospores for survival
Endospores
Mutualism with Eukaryotes
mychorrhizae: fungus
– assist plants in the uptake of
phosphorous
– mychorrizae gain nutrient from plant
Mutualism
nitrogen fixers: fix nitrogen
and make it available for
the use by their partner
plant
– most common is
Rhizobium, a
microorganism found in
many root nodules
Rhizobium in root nodules
Nitrogen Cycle
Carbon cycle
Mutualism: microorganisms and the
world
microorganisms and herbivores
– animal with a rumens (cow) or cecums
(horse) need microorganisms to digest the
plant food they ingest
Bacillus in a
cow rumen
Microorganisms in Sewage Treatment
decreasing biochemical
oxygen demand (BOD)
decreases impact of
sewage on the
environment
BOD is the amount of O2
needed for microbial
decomposition of the
organic material in a
sample
Grit chamber
Biological filter
Clarifier
Microorganisms in Sewage
Treatment
if not treated the high BOD found in sewage could
deplete the O2 level in the receiving water
in other words if raw sewage is deposited into a lake or
stream without treatment, it would effectively suck the
oxygen out of the water, leaving very little for the fish and
other organisms
Microorganisms in Sewage Treatment
sewage treatment is a controlled process that
strives to eliminate the excess organic material,
thus diminishing the BOD
– most of the removal of organic matter is done
by microorganisms
bacterial filaments
Microorganisms and Water Treatment
and Testing
municipal water supplies
are tested and treated for
the removal of pathogenic
microorganisms and
chemicals
– this is done with the
use of chemicals
Microorganisms and Solid Waste
Treatment
the elimination of organic waste
material can be enhanced by
microorganisms
– increase cost to separate organic
material from inorganic (glass,
metal, plastic)
– composting: natural decomposition
of organic solid materiel results in
excellent fertilizer
Compost
microorganisms are
needed to breakdown
the organic material
Bioremediation:
use of microorganisms to eliminate or make
harmless pollutants in an environment
pollutants removed
can include
– organic solvents
– toxic chemicals
– hydrocarbons
oil spill
Bioremediation
introduces specific organisms to the polluted area
– many toxic substances are man-made/new to the
environment (xenobiotics)
– no time for naturally occurring microbes to have
evolved biochemical pathways for their degradation
scientists are trying to develop new microbes for the
degradation of environmental polluters
Cleaning an oil spill
Bioremediation
scientists are also making use of organisms already
found in the environment
– enhance their requirements for growth, such as
nutrition or water availability
Bacteria in an oil spill
Why Bioremediation?
current methods of controlling some
environmental polluters are incineration or
storage in land fills, which result in
– more pollution
– health risks
bioremediation is
– inexpensive
– publicly accepted
– non-polluting (ideally)
– in situ treatment (at the site)