Ch 27 Environmental Microbiology

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Ch 27 Environmental Microbiology

• What do Microbes do?
• How can we use this to our advantage?

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Microbes have small genomes but can

• Not do a lot, but what do, do well
• Extremophiles
• Microbes live in extreme conditions of
• Temperature
• Acidity
• Alkalinity
• Salinity
• Eubacteria vs Archaebacteria

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Biological definition of Organismal interactions

• Symbiosis a relationship between two different
  species
• Parasitism one org gets nutrients from another
• Mutualism both partners benefit
• Commensalisms one benefits more

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• Other examples?

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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

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The Biogeochemical cycles
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The carbon cycle

• Photoautotrophs
• Chemoautorophs
• Both convert inorganic forms of carbon into
  organic forms using external sources of energy

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Chemoheterotrophs release

• Inorganic form of carbon (CO2) to complete the
  cycle.
• Non living sinks include
• CaCO3 and fossil fuels

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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

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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 acids

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• Fertilization and microbes
• Cyanobacteria for a symbiosis with small floating
  fern Azolla in rice paddy waters.

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Sulfur cycle

• Plants and certain microbes can use SO42- to make
  amino acids
• H2S is oxidized to form SO42-

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Sulfur Cycle
Microbial decomposition
Proteins and waste products
Amino acids
Microbial dissimilation
Amino acids (SH)
H2S
Thiobacillus
H2S
SO42 (for energy, by respiration)
Microbial plant assimilation
SO42
Amino acids
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The Phosphorous Cycle
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The Phosphorus Cycle

• Inorganic phosphorus is solubilized by microbial
  acids
• Made available to plants and other microbes
• Is soluble in water
• Combines with calcium in calcium phosphate
  deposits of ancient seas.

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Life Without Sunshine

• Primary producers in most ecosystems are
  photoautotrophs
• Primary producers in deep ocean and endolithic
  communities are chemoautotrophic bacteria

Provides energy for bacteria which may be used to
fix CO2
H2S
SO42
Calvin Cycle
CO2
Sugars
Provides carbon for cell growth
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Use of chemicals in soil and water

• Many man made chemicals do not biodegrade because
  they are not made by living organisms
• Why?

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Decomposition by Microbes
Components of agent orange
Figure 27.8
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Bioremediation

• Use of microorganism to remove pollution
• Cheaper
• Can use natural organism
• Is helped by preventing limited nutrients

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Solid Municipal Waste piles

• Many municipal waste piles are inefficiently run
  because they are dry and anaerobic

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Aquatic conditions

• Biofilms are composed of whole communities of
  microbes that are metabolically diverse
• Bodies of water are naturally set up to process
  waste
• 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

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Freshwater Donation
Figure 27.12
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Roll of microorganism in water quality

• Biomagnifications
• Indicators of fecal contamination
• Blooms
• Eutrophication

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Waterborne Diseases
Table 27.2
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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
  35C
• Fecal Coliforms predominantly E. coli are used to
  indicate the presence of human fecies

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Coliforms

• Aerobic or facultatively anaerobic,
  gram-negative, nonendospore forming rods that
  ferment lactose to acid gas within 48 hr, at
  35C
• Indicator organisms
• Used to detect fecal contamination
• MPN
• Most probable number/100 ml of water

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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

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Sewage Treatment

• The quality of life that we see in our first
  world countries is due to our treatment of sewage
• Primary treatment removal of solid materials
  (35 BOD)
• Secondary treatment Reduction of BOD by the
  metabolic (95BOD) degradation of organic matter

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More sewage treatment

• BOD biochemical oxygen demand
• Tertiary provides essentially drinkable water is
  much more expensive to do

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Activated Sludge
Figure 27.20a,b
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Alternative treatments of sewage

• Septic tanks
• Oxidation ponds

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Sludge produced by sewage treatment plants.
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Anaerobic Sludge Digester

• CO2 4 H2 ? CH4 2 H2O
• CH3COOH ? CH4 CO2

Figure 27.23