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Biodegradation of Chemicals

Biodegradation of Chemicals. Natural organics typically degraded quickly Most xenobiotics not as easily broken down Synthetic chemicals are often recalcitrant Chemicals leaching into ground water is a growing problem Sources are landfills, pesticides and illegal dumps Bioaccumulation.

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Biodegradation of Chemicals

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  1. Biodegradation of Chemicals • Natural organics typically degraded quickly • Most xenobiotics not as easily broken down • Synthetic chemicals are often recalcitrant • Chemicals leaching into ground water is a growing problem • Sources are landfills, pesticides and illegal dumps • Bioaccumulation

  2. Small differences in structure can make a big difference in biodegradability

  3. Bioremediation • use of microbes to detoxify or degrade pollutants • Oil spills provide a dramatic example • Bioaugmentation

  4. Solid municipal waste (garbage) is frequently placed in landfills • 150 million tons annually in US • Mostly anaerobic conditions not conducive to the biodegradation of organic material • Promotes activity of methanogens

  5. Composting may reduce amount of organic material entering landfills • May be used as organic fertilizerdepending on origin

  6. Aquatic Microbiology • Bacteria don’t often exist as single species in isolated colonies • Often form biofilms attached to a surface or less often as floating floc • Essential in proper sewage treatment • Important health factor • Prevention involves incorporation of anti-bacterial agents into potential colonization surfaces

  7. Benefits of biofilm formation: • Cell-to-cell communication • Share nutrients • sheltered from harsh environmental conditions • Easier sharing of genetic information

  8. Form pillar-like structures with channels • Primitive circulatory system • Individual bacteria and clumps of slime break away • Establish new biofilms

  9. Large numbers of microbes in a body of water indicate high nutrient levels • Sewage or agricultural contamination • Estuaries • Aquatic microbes in nutrient poor systems may have appendages or holdfasts for attachment • Increases contact with nutrients • Caulobacter and Hyphomicrobium

  10. Freshwater Microbiota • Populations affected by light and oxygen availability • Oxygen does not diffuse into water well • movement increases availability • Littoral zone • Limnetic zone • Profundal zone • Benthic zone

  11. Seawater Microbiota • Divides into zones based on light and O2 availability • Includes abyssal zonedominated by archaea • Phytoplankton • microscopic photosynthetic organisms • Mostly cyanobacteria and single-cell algae • Form basis of oceanic food chain • food source for increasingly larger consumers (Protozoa, zooplankton, fish)

  12. Bioluminescence • Luminescent bacteria have luciferase enzyme • Picks up electrons and emits energy as photon of light • Symbiotic relationships with deep water fish • Aids fish in capturing prey • Benefit to microbe? Luminous organ

  13. Water Pollution • Chemical contamination • Industrial wastes may leach chemicals resistant to biodegradation • Agricultural runoff may have excess nitrates and phosphates, as well as pesticide contamination

  14. Algal Blooms • Biodegradable detergents and agricultural runoff can lead to algal blooms • May lead to eutrophication • Red tide

  15. Industrial water pollution includes mercury from paper production • Mercury is converted to a soluble compound by microbes and accumulates in fish • Coal mining wastes are high in iron and sulfur • Microbes convert sulfur to sulfates lowering pH which causes insoluble iron hydroxide to form and precipitate

  16. Biosensors may be used to detect pollutants Luciferase FMNH2 FMN + photon Vibrio fisheri

  17. Microbial water pollution is of primary interest • especially pathogens • Moving water below the surface is filtered • water from deep springs and wells is usually good quality • Fecal contamination is the most dangerous form of water pollution • Many diseases are spread through oral-fecal route

  18. Water Purity Tests • Monitored to determine the safety of water • potability • Aimed at detecting indicator organisms • Criteria include: • Present in human feces in high numbers • Survive in water as well as pathogens would • Detectable by simple tests

  19. Coliforms commonly used to detect contamination of drinking water • Aerobic or facultatively anaerobic, gram-negative, non–endospore forming rods • Ferment lactose to acid & gas within 48 hr, at 35°C • Not all are limited to intestinal tract of animals • Most tests specific for fecal coliforms • E. coli is dominant fecal coliform

  20. MPN - most probable number/100 ml of water Quantitative but looks at total coliforms

  21. ONPG/MUG Test -galactosidase ONPG yellow indicates coliforms - glucuronidase MUG Blue indicates fecal coliforms Qualitative only but distinguishes fecal coliforms

  22. Membrane filtration, utilizing differential media like Eosin Methylene Blue Agar (EMB), is quantitative and specific for fecal coliforms

  23. PCR utilizing gene specific primers may also be used to detect microbes present due to sewage contamination • Specific group of fecal Streptococci (Enterococci) used as indicators in recreational waters

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