Ch 27 Environmental Microbiology

Ch 27 Environmental
What do Microbes do?
How can we use this to our
Microbes have small genomes
but can
• Not do a lot, but what do, do well
• Extremophiles
– Microbes live in extreme conditions of
• Eubacteria vs Archaebacteria
Biological definition of Organismal
• Symbiosis: a relationship between two
different species
– Parasitism: one org gets nutrients from
– Mutualism: both partners benefit
– Commensalisms: one benefits more
• Other examples?
Biogeochemical cycles
• Matter can neither be created or destroyed
• A constant amount of matter in the
environment must be recycled
• Microbes are essential in the conversion of
nutrients into organic and usable formats
• Microbes are essential in the conversion of
nutrients into the inorganic form
The Biogeochemical cycles
The carbon cycle
• Photoautotrophs
• Chemoautorophs
• Both convert inorganic forms of carbon
into organic forms using external sources
of energy
Chemoheterotrophs release
• Inorganic form of carbon (CO2) to
complete the cycle.
• Non living sinks include
• CaCO3 and fossil fuels
The nitrogen cycle
• Local shortages because of Nitrogen stuff
• Microbes decompose proteins form dead
cells and release amino acids
• Ammonia is liberated by microbial
ammonificaiton of amino acids
• Ammonia is oxidized to produce nitrates
for energy by nitrifying bacteria
More nitrogen stuff
• Denitrifying bacteria reduce nitrogen in
nitrates to molecular nitrogen
• N2 is converted into ammonia by nitrogen
fixing bacteria
• Ammonium and nitrate are used by
bacteria and plants to synthesize amino
• Fertilization and microbes
• Cyanobacteria for a symbiosis with small
floating fern Azolla in rice paddy waters.
Sulfur cycle
• Plants and certain microbes can use
SO42- to make amino acids
• H2S is oxidized to form SO42-
Sulfur Cycle
Proteins and waste products
Amino acids (–SH)
Microbial decomposition
Microbial dissimilation
SO42– (for energy, by respiration)
Microbial & plant assimilation
Amino acids
Amino acids
The Phosphorous Cycle
The Phosphorus Cycle
• Inorganic phosphorus is solubilized by
microbial acids
• Made available to plants and other
• Is soluble in water
• Combines with calcium in calcium
phosphate deposits of ancient seas.
Life Without Sunshine
• Primary producers in most ecosystems are
• Primary producers in deep ocean and
endolithic communities are
chemoautotrophic bacteria
H2 S
Provides energy for bacteria
which may be used to fix CO2
Calvin Cycle
Provides carbon for cell growth
Use of chemicals in soil and water
• Many man made chemicals do not
biodegrade because they are not made by
living organisms
• Why?
Decomposition by Microbes
Components of agent orange
Figure 27.8
Use of microorganism to remove pollution
Can use natural organism
Is helped by preventing limited nutrients
Solid Municipal Waste piles
• Many municipal waste piles are
inefficiently run because they are dry and
Aquatic conditions
• Biofilms are composed of whole communities of
microbes that are metabolically diverse
• Bodies of water are naturally set up to process
• Tend to grow in presence of oxygen and light
• Use is best when oxygen content is increased
• Phytoplankton in oceans are primary producers
in the open ocean
Freshwater Donation
Figure 27.12
Roll of microorganism in water
Indicators of fecal contamination
Waterborne Diseases
Table 27.2
Water quality tests
• Coliforms are aerobic or facultatively
anaerobic, gram negative non endospore
forming rods that ferment lactose with the
production of acid and gas within 48 hours
of been placed in a medium at 35’C
• Fecal Coliforms predominantly E. coli are
used to indicate the presence of human
• Aerobic or facultatively anaerobic, gramnegative, non–endospore forming rods that
ferment lactose to acid + gas within 48 hr, at
• Indicator organisms
– Used to detect fecal contamination
– Most probable number/100 ml of water
Water Treatment
• Water held in a holding reservoir long
enough that suspended matter settles
• Flocculation treatment uses a chemical
such as alum to coalesce and settle
colloidal material
• Filtration removes protozoan cyst and
other microbes
• Drinking water is disinfected with chlorine
to kill remaining pathogenic bacteria
Sewage Treatment
• The quality of life that we see in our first
world countries is due to our treatment of
• Primary treatment: removal of solid
materials (35% BOD)
• Secondary treatment: Reduction of BOD
by the metabolic (95%BOD) degradation
of organic matter
More sewage treatment
• BOD biochemical oxygen demand
• Tertiary provides essentially drinkable
water is much more expensive to do
Activated Sludge
Figure 27.20a,b
Alternative treatments of sewage
• Septic tanks
• Oxidation ponds
Sludge produced by sewage
treatment plants.
Anaerobic Sludge Digester
• CO2 + 4 H2  CH4 + 2
H 2O
• CH3COOH  CH4 +
Figure 27.23

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