Environmental Microbiology

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Environmental Microbiology

• Water microbiology

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Water microbiology

• Cyanobacteria compose a large part , form the
  basis of the oceanic food chain
• Plankton microscopic aquatic organisms
• Phytoplankton support of ocean life is
  dependent on photosynthetic microscopic ocean
  life
• Red tides of toxin-producing phytoplankton are
  caused by excessive nutrients from oceanic
  upwellings or terrestrial wastes
• Zooplankton- animal life of the plankton family
• Are eventually prey for fish

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Water microbiology

• Thermal vent bacteria are the primary producers
  of the deep ocean floor
• Lake health usually involves bacteria
• Oligotrophic lakes have deep, clean water, low
  biological oxygen demand (B.O.D.), high dissolved
  oxygen (D.O.), high amounts of game fish

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Lake health

• Eutrophic lakes have shallow, murky water, high
  B.O.D., low D.O., few or no game fish
• Caused by an overabundance of nutrients in lakes
  and streams

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Water quality

• Tests for water purity are aimed at detecting
  indicator organisms
• Microbe (indicator) must be consistently present
  in human feces in substantial numbers
• Detectable by simple tests
• Coliform bacteria are the usual indicator
  organisms used in the U.S. for testing water
• Defined as aerobic, facultatively anaerobic, gram
  - , non-endospore-forming, rod-shaped, lactose
  fermenters that form gas lt 48 hours
• E coli is the predominant fecal coliform (human
  intestinal inhabitants) o)

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Water quality

• Test for E coli with ONPG (forms a yellow color)
  and MUG (fluoresces blue when exposed to long
  wave U.V. light)
• Useful indicator organisms for water sanitation
• Due to E coli presence, water may contain Giardia
  lamblia and Cryptosporidium cysts which are
  resistant to chemical disinfection both are 100X
  more resistant to treatment than viruses)

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Water quality

• There are acceptable coliform limits
• Water treatment is designed to produce water
  which is free of pathogens, not sterile water
• Drinking water is obtained either from surface
  reservoirs or aquifers (underground)
• Potable water is safe to drink
• Clear water doesnt mean that it is potable

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Water treatment

• What happens to that water that is used to do
  laundry, shower, flush, etc??
• Primary sewage treatment
• Large, floating material form incoming waste
  water are screened out
• Sewage then flows to settling chambers where
  skimmers remove floating debris (such as oil and
  grease)
• Goes to sedimentation tanks so that solid
  material settles (sludge) This removes 50 of
  the suspended solids Flocculent is added to
  increase sedimentation
• The effluent (liquid) then undergoes secondary
  treatment
• Primary treatment removes 30 of the B.O.D. or
  the biodegradable matter

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Secondary treatment

• Us designed to remove organic matter thereby
  reducing the B.O.D.
• Undergoes strong aeration which causes bacteria
  to grow in order to oxidize the organic matter to
  CO2 and H2O
• Use activated sludge system where oxygen is
  pumped into effluent and some sludge is added
  (sewage metabolizing microbes)
• Transferred to settling tank, clear effluent is
  disinfected and discharged (removes 75-95 of
  B.O.D.) OR

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Secondary treatment

• Trickling filters are used
• Sewage is sprayed over a bed of rocks (or
  plastic) which has a biofilm of aerobic microbes
  growing
• Most of the organic matter is oxidized (80-85
  B.O.D.)
• Disinfection using chlorination before
  discharging into ocean, streams or spray
  irrigation

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After secondary treatment

• Sewage can be used as drinking water if filtered
  and passed through a reverse osmosis system to
  remove microbes
• Then exposed to U.V. light or other disinfectant

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Tertiary treatment

• The effluent from secondary treatment contains
  some B.O.D. and 50N2 and 70 P which can affect
  ecosystems
• Tertiary treatment is designed to remove all of
  it
• Depends mostly on physical and chemical treatment
• Precipitate out the phosphorus
• Charcoal and/or sand filters use to remove
  chemical and small particulate matter
• Nitrogen is converted to ammonia and discharged
  into the air

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Tertiary treatment

• Purified water is chlorinated
• Provides water which is suitable for drinking
• Very costly process
• Secondary treatment is less costly when water is
  used for irrigation only, soil acts as a
  trickling filter before water reaches the ground
  water or surface water

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Water borne diseases

• Salmonella typhii causes typhoid fever
• Multiplies in phagocytic cells of mainly the
  spleen and liver
• Symptoms fever, diarrhea, abdominal pain
• Invades gall bladder resulting in chronic
  carriers such as Typhoid Mary who was a cook

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Salmonella typhii

• Humans are the exclusive hosts, spread only in
  human feces
• Cycle of infection broken with proper sewage
  disposal, water treatment and food sanitation
• Vaccine not normally administered in developed
  countries. With this, immunity only exists for a
  few years
• Life long immunity is conferred after infection
  and recovery from the illness

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Vibrio cholera

• Causes cholera
• Grows in the small intestine, produces exotoxin
• Symptoms sever muscle cramping, violent
  vomiting, up to 3-5 gallons of diarrhea/day
• Excess water and mineral electrolytes lost can
  cause shock, death
• Fever is usually not present

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Vibrio cholera

• Endemic in Asia, particularly India
• It is a worldwide problem where control of
  elimination of wastes is not practiced
• Oral electrolyte therapy (replacement of lost
  fluids and electrolytes is more effective than
  tetracycline administration
• Untreated has a 50 mortality rate

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Shigella flexneri

• Causes shigellosis, bacillary dysentery
• Symptoms abdominal cramps, diarrhea with mucus
  and blood
• Primary site of the disease is the large
  intestine
• Some immunity results from recovery
• No vaccine exists
• Choice of antibiotic therapy is fluoroquinolones

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Entamoeba histolytica

• Protozoan which causes amoebic dysentery
• Usually from unsanitary food or water
• Is usually killed by water chlorination

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Giardia lamblia

• Causes giardiasis
• Flagellated protozoan
• Prolonged diarrheal disease
• Characterized by nausea, flatulence, distinctive
  odor of H2S gas can be detected in breath and
  stools
• May interfere with food absorption
• Common in the wilderness water sources
• Pathogen is shed by wild animals and consumed
  from fresh water
• Boil all water from wilderness sources

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Hepatitis A

• Typical entrance via oral route
• Multiplies in the lining of the intestinal tract
• Virus is shed in feces and can be detected in
  blood and urine
• Virus can survive several days on surfaces such
  as cutting boards
• Can be infected from water, foods cleaned in
  water, sometimes shellfish
• Survives in chlorine at he concentration used in
  water treatment

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Escherichia coli

• Causes travelers diarrhea
• Enterotoxigenic E coli is not part of our normal
  flora
• Produces a watery diarrhea resembling mild
  cholera accompanied by nausea and a low grade
  fever
• When traveling, carry anti-diarrheal medications,
  Peptobismol
• Dont use water for teeth brushing, washing
  fruits and veggies if not purified
• boil it, peel it or dont eat it

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Poliomyelitis

• A virus which has three serotypes
• Vaccine provides immunity to all three
• Salk vaccine series uses viruses which have been
  inactivated using formalin
• Sabin vaccine, the oral one, uses three living
  attenuated strands. Immunity achieved resembles
  having been naturally infected
• Occasionally, the first dose administered type
  3 may revert to virulence and cause disease in
  children

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Soil microbiology

• Made up of minerals, living organisms (including
  fungi, microscopic bacteria) and humus which is
  the dead or decaying part of dirt
• One gram of soil can contain millions? billions
  of bacteria, most of which are beneficial

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• Barren rock ? soil formation begins with pioneer
  organisms, lichens (which are symbiotic organisms
  made up of algae and fungi) and cyanobacteria
• Saprophytes or decomposers recycle nutrients
  returning C, N, P,S and Fe to the soil
• Biodegradable products can be broken down by
  organisms

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• Nitrogen recycling has long been practiced in
  farming (even if they didnt understand the
  mechanism of bacterial action)
• Crop rotation/ us of manure both involve bacteria
  re-supplying nitrogen to the soil by nitrogen
  fixation
• Nitrogen cycle involves fixation, nitrification
  and denitrification

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• Nitrogen fixation
• 78 of the air is in the form that plants and
  animals cannot use directly
• Bacteria residing on the root nodules of legumes
  as well as some free living soil bacteria can use
  the nitrogen gas and fix it into a form that
  can be used NO3-

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Other environmental microbes

• Bioremediation uses microbes to detoxify or
  degrade pollutants
• Natural bioremediation is enhanced with
  fertilizer (NP)
• Bioaugmentation makes luse of certain microbes
  selected for growth (or genetically modified) on
  petroleum products

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• Acid rain which is created by burning fossil
  fuels (gives off sulfur which is converted to
  sulfuric acid in the atmosphere) can be reduced
  or assimilated into bacteria
• Biological pest control
• Bacillus thuringiensis creates a diamond shaped
  crystal toxic to insects that ingest it
• Kills catepillars in farming

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• Bioluminescent fish emit light
• Bacteria are luminescent and establish a
  symbiotic relationship with deep sea dwelling
  fish
• Glow helps to attract and capture prey
• Organisms have the enzyme luciferase which picks
  up electrons from the flavoproteins of the ETS
  and emits electrons as photons of light

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Global warming

• What do bacteria have to do with global warming??
• Global warming is an increase in heat retention
  of the atmosphere due to carbon dioxide and
  methane
• Referred to as the greenhouse effect
• Cyanobacteria fix carbon dioxide into organic
  matter
• Chemoautotrophs such as Thiobacillus fix carbon
  dioxide into organic matter using hydrogen
  sulfide gas for energy

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Global warming

• Methane, an even more potent greenhouse gas than
  carbon dioxide is used by prolific sea dwelling
  bacteria that use the escaping methane gas as an
  energy source (ten trillion tons of methane is
  contained here) o)