Microorganisms and the environment

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Microorganisms and the environment two major
roles primary producers photosynthesis
algae cyanobacteria decomposers
mineralization fungi, bacteria,
protozoa other roles food source for other
organisms
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Microorganisms and the environment two major
roles primary producers photosynthesis
algae cyanobacteria decomposers
mineralization fungi, bacteria,
protozoa other roles food source for other
organisms contribution to global
warming greenhouse effect CO2, methane as
greenhouse gases rumen microorganism mineraliz
ers
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Microorganisms and the environment factors
which limit growth water energy light or
chemical temperature pH salinity nutrients
often either low or limiting some
sequester iron which limits availability
natural substances antibiotics low
nutrients competition intense may form biofilms
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Biogeochemical cycling carbon and oxygen
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Biogeochemical cycling nitrogen
ammonification
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Biogeochemical cycling Fe2 Fe3
Hg2 acid rain biomagnification
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Biogeochemical cycling Fe2 Fe3
Hg2 acid rain biomagnification
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Biodegradation natural organics subject to
biodegradation starch, proteins, lipids,
etc. Chitin, lignin, cellulose more
recalcitrant other compounds hydrocarbons,
oil, etc. detergents biocides PCB
polychlorobiphenyl
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Bioremediation degrade pollutants in situ
stimulate natural population limitations
ability of organisms nitrogen, phosphorus,
etc. Temperature genetically
engineered organisms limitations same
competition with natural population
survival of organisms concern over DNA transfer
to natural population
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Environments aquatic and terrestrial Aquatic
freshwater and marine some unique
environments or niches nutrient levels
vary greatly, low to high organic sinks (bottom
rich, no oxygen) upwelling of water
nutrient concentrations high near
objects microbes attach to surfaces forming
biofilm monolayer adds more microbes, becomes
stratified mixed population
complexity increases microbial mat
metabolism becomes complex SO4-2 ? S-2 in
core, S-2 ? S at surface aerobes and
anaerobes may be some photosynthetic organisms
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BiofilmsResistance to antibiotics in chronic
bacterial infections is a difficult and sometimes
deadly medical problem. During the development
of a chronic infection, bacteria often undergo
what could be called a lifestyle change instead
of living as individual organisms, the bacteria
form community structures known as biofilms that
are like cities of bacteria. Bacteria in
biofilms are extremely resistant to antibiotics.
Bacterial biofilms are dense, organized
cellular communities encased in a self-produced
slime. Living in groups gives the bacteria
properties that they do not have as individuals.
In addition to being highly resistant to
antibiotics, biofilms are also impervious to the
bodys natural immune system. Examples of
biofilm infections include lung infections in
patients with cystic fibrosis, wound infections
in patients with diabetes and burns, heart valve
infections, as well as most medical device
infections.
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BiofilmsOne important difference (between acute
and chronic infections) is that the opportunists
live as biofilm communities in the host.
Biofilms are ubiquitous in nature. In this state
the bacteria tolerate the highest deliverable
doses of antibiotics which basically make them
impossible to eradicate. Biofilm infections are
getting more and more common due to growing
utilization of medical implants (catheters,
artificial heart valves, etc.) Such artificial
surfaces create ideal environments for the
development of biofilm infections. Taking the
development of age distribution into account,
this will become one of the major medical
problems of the 21st century that urgently needs
attention.
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Environments aquatic and terrestrial Aquatic
freshwater and marine some unique
environments or niches nutrient levels
vary greatly, low to high organic sinks (bottom
rich, no oxygen) upwelling of water
nutrient concentrations high near
objects microbes attach to surfaces forming
biofilm monolayer adds more microbes, becomes
stratified mixed population
complexity increases microbial mat
metabolism becomes complex SO4-2 ? S-2 in
core, S-2 ? S at surface aerobes and
anaerobes may be some photosynthetic organisms
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Microbial communities wide variety of
organisms photosynthetic chemoheterotrophic che
molithotrophic phytoplankton algae,
diatoms zooplankton protozoa bacteria
and archaebacteria population dictated by
nutrients, pH, temperature, oxygen marine
depths (light a factor) and temperature
human impact?? added N, P, oil, pesticides,
etc. added bacteria (runoff, etc.)
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Freshwater environments rivers and lakes
nutrient levels oligotrophic vs.
eutrophic eutrophic environments stratified
(aerobic at top) eutrophication rivers
nutrient influx dramatic (runoff,
sewage) organisms in biofilms and mats
water quality measures BOD and COD limits on
BOD and COD in wastewater
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Sewage treatment primary remove
particulates (ppt, screen, settling
tanks) removes 20-30 BOD secondary
aerobic for removal of dissolve organics removes
90-95 BOD, most pathogens tertiary remove
N and P via chemical precipitation carbon
filters or plants/wetlands to remove organics
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Water purification and pathogens numerous
water-borne pathogens viruses, bacteria,
protozoa sedimentation some settle with
solids settling basin add alum and lime to
coagulate some pathogens precipitate out
filtration thru sand rapid flow physical
trapping removes up to 99 slow flow biofilm
on sand grabs and removes bacteria Giardia
cysts not trapped by rapid, better by slow
Cryptosporidium smaller, harder to remove
disinfection chemical treatment chlorine
high levels needed carcinogens ozone
Cryptosporidium resistant to disinfection
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Water purification and pathogens test for
purity Standard Analysis of Water
coliform as indicator E. coli, E. aerogenes, K.
pneumoniae presumptive fermentation of lactose
to acid and gas confirmed brilliant green bile
broth to acid and gas completed EMB agar,
Gram-stain, lactose broth, IMViC Groundwater
quality subsurface water filtration through
the ground removes most organisms septic
systems anaerobic tank for digestion of
organics water into leach field for aerobic
oxidation of organics N P to water
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Marine environment temperature about
5C nutrient levels low, esp. P and N
pollution
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Terrestrial environment variety of surfaces
water and nutrients vary sandy vs.
loam oxygen levels also vary organic matter
humus holds water holds
nutrients Plant-microbe interaction microbes
in close association with all of plant, esp.
root microbes cause exudation release of
nutrients by plant generates rhizosphere
region high in microbes microbes provide
nutrients for plant also extreme Rhizobium and
legumes microbes enhance water availability
for plant
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Mycorrhizae fungus-root association ectomyco
rrhizal association endomycorrhizal
association wheat, corn, beans, tomatoes,
apples, oranges, etc. may increase nutrient
availability may aid in water uptake, esp. in
arid soils Endophytes fungi and bacteria which
live in plants some mutualistic plant
resistant to chewing insects (alkaloids)
some parasitic reduce genetic variability by
sterilizing host cotton, potatoes Agrobacterium
tumifaciens tumor-like growth or gall