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Ch 27 Environmental Microbiology

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1 Ch 27 Environmental Microbiology
What do Microbes do? How can we use this to our advantage?

2 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

3 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

4 Fig 27.5

5 Other examples? Mycorrhizae
Endomycorrhizae or vesicular arbuscular mycorrhizae. Endo within And ectomycorrhizae, on the outside oaks ect.

6 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

7 The Biogeochemical cycles
Also termed biological fire

8 The carbon cycle Photoautotrophs Chemoautorophs
Both convert inorganic forms of carbon into organic forms using external sources of energy

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

10 Discuss how carbon moves and the sinks or storage areas

11 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 Again, look at how this nutrient moves and what causes local shortages

12 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 Denitrification occurs in watterlogged soils without air. The nitrates of agricultural fertilizer can act as an electron acceptor


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

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

16 Dissimilation Assimilation Oxidation Anaerobic rspiration

17 Sulfur Cycle Proteins and waste products Amino acids Amino acids (–SH)
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

18 The Phosphorous Cycle

19 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.

20 Life Without Sunshine Primary producers in most ecosystems are photoautotrophs Primary producers in deep ocean and endolithic communities are chemoautotrophic bacteria H2S SO42– Provides energy for bacteria which may be used to fix CO2 Calvin Cycle CO2 Sugars Provides carbon for cell growth

21 Use of chemicals in soil and water
Many man made chemicals do not biodegrade because they are not made by living organisms Why?

22 Decomposition by Microbes
Weed be gone a biodegradable herbicide Agent orange, a resilient herbicide Components of agent orange Figure 27.8

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

24 Solid Municipal Waste piles
Many municipal waste piles are inefficiently run because they are dry and anaerobic

25 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

26 Freshwater Donation Figure 27.12

27 Roll of microorganism in water quality
Biomagnifications Indicators of fecal contamination Blooms Eutrophication

28 Waterborne Diseases Table 27.2

29 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 fecies

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

31 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


33 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 (95%BOD) degradation of organic matter

34 More sewage treatment BOD biochemical oxygen demand
Tertiary provides essentially drinkable water is much more expensive to do


36 Activated Sludge Figure 27.20a,b

37 Alternative treatments of sewage
Septic tanks Oxidation ponds



40 Sludge produced by sewage treatment plants.

41 Anaerobic Sludge Digester
CO2 + 4 H2  CH4 + 2 H2O CH3COOH  CH4 + CO2 Most methan is derived from reduciton of carbon dioxide by hydrogen gas. Other methan producing microbe split acetic acid to yeald methan and carbon dioxide. Figure 27.23

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