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Chapter 2

Chapter 2. Topics covered. Positions of microorganisms in the “tree of life” Environments with important microbial populations Viruses in the environment Protozoans with an environmental component to its life cycle. Tree of Life. Eukarya are more closely related to Archaea than to Bacteria.

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Chapter 2

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  1. Chapter 2 Topics covered • Positions of microorganisms in the “tree of life” • Environments with important microbial populations • Viruses in the environment • Protozoans with an environmental component to its life cycle

  2. Tree of Life

  3. Eukarya are more closely related to Archaea than to Bacteria

  4. Microorganisms live as communities in nature Syntrophic Process:Each microbial population has a specific role to play to sustain the community Archaea-red Bacteria-green Antje Boetius, Katrin Ravenschlag, Carsten J. Schubert, Dirk Rickert, Friedrich Widdel, Armin Gieseke, Rudolf Amann, Bo Barker Jørgensen, Ursula Witte and Olaf Pfannkuche. Nature 407, 623-626(5 October 2000) 5 um

  5. Human oral cavity Tooth surface

  6. In your mouth…. • Actinomyces naeslundii and Streptococcus oralis are regarded as pioneer colonizers of tooth surfaces. • Fusobacterium and Veillonella facilitate formation of dental plaque.

  7. Dentistry is a form of practice of applied microbiology: the control of microbial communities in the oral cavity Gingivitis Tooth decay Porphyromonas gingivalis Streptococcus mutans Lactobacillus

  8. Wastewater Treatment Better understanding of operating conditions in treatment facility to avoid phenomenon such as “bulking”depends on better understanding of community function and interactions http://www.environmental-center.com/consulting/watermatters/microscopic.htm#1

  9. In the mountains... • Alpine streams and lakes - • Are they pristine? • McFeters and others, 1970’s, studies in Grand Teton National Park • Microbiological findings: Little effect of human presence, more from native animals • Biofilms • Giardia is common in streams and lakes around Bozeman • Source: humans ►native animals?

  10. Pine Creek Biofilm SEM (Bar = 2.0 μm) Microorganisms are attached to submerged surfaces

  11. bacterialcells EPS Biofilms on rocks clean the water just as those in engineered wastewater treatment plants substratum

  12. In the soil…. Legume nodules Seed manufacturers now inoculate seeds with specific strains of nodule-forming bacteria. Why? Nodule contains a pure culture of a N2-fixing bacterium (very rare to have pure culture in nature)

  13. Viruses in the Environment • Bacteriophage • role in nature: control bacterial pops • as many as 108 particles/ml in rivers, lakes, estuaries

  14. Viruses in the Environment • Bacteriophage • Control bacterial populations • transfer genes between bacterial populations • Hard to observe and quantify • Estimated that phage DNA contributes 3.5% of total DNA recovered from freshwater, estuarine and offshore marine environments-more than that contributed by any other life form. • access to a phage-host system that comes from the environment enables genetic manipulation of novel bacteria to carry out important functions for society • Examples?

  15. Viruses from thermal soils and springs in Yellowstone National Park Sulfolobus spindle- shaped viruses capsid- protein coat of virus used to encapsulate & deliver chemicals to target tissues Wiedenheft et al., J. Virology (2004) 78:1954

  16. Physicochemical Characteristics of Viruses • Negatively charged surfaces at neutral pH • form electrical double layer (Stern layer) • Diffuse layer (Gouy) contains more counterions at lower conc. • Charge on virus surface leads to strong interactions Virus surface with soil and sediment particles. Hydrophobic groups on virus coat also promotes interactions with hydrophobic soil particles.

  17. Infective nature of viruses Zoonosis Bird, rodent, feline • More than 70% of all plant and animal infections are due to viruses with RNA genomes • Viruses have many mechanisms of transmission Vector-borne Environment HSV-2: human herpes virus 2 HBV: hepatitis B virus CMV: cytomegalovirus

  18. New emerging viral diseases • Ebola • First outbreak in 1976 in the Democratic Republic of the Congo (Zaire) • West Nile virus • Mode of transmission to humans?

  19. Viral particles: may or may not be infections Virions: infectious particles Viroids: free RNA sequences able to reproduce in several different hosts Prions: free proteinaceous infectious particles unable to elicit immune response. (Creutzfeldt-Jacob disease in humans, bovine spongiform encephalopathy (BSE) “mad cow” (plants) Know to causes 16 diseases

  20. Protozoans • 18S rRNA based classification indicates that single-celled protozoa are polyphyletic (developed from more than one ancestor) • Similar • morphology • physiology • reproduction • Ecology • Most protozoa are found in aquatic habitats Class Hymenostomea Class Peritrichea Class Spirotrichea

  21. Giardia lamblia Protozoans • Free-living outside host and/or parasitic depending on environmental conditions • flagellates (Giardia) • Ciliates (Paramecium) • Can reproduce asexually or sexually

  22. Protozoan Ecology • Beneficial roles of protozoa in the environment • Protozoans graze on bacteria, algae and fungi, keeping their biomass in check. • Serve as the base of the food web in many aquatic systems • 200 cells/ml in eutrophic lakes (can comprise 60% of total zooplankton) • Degradation of complex organic matter (cellulose). This is referred to as a saprophytic lifestyle. • cultivated in sewage treatment.

  23. Protozoan relationships with host • Commensalism • One organism uses another for food, shelter and transport, but causes no ill effect to the other • Symbiosis • Both host and parasite benefit by association • Tissue parasitism • Parasite feeds on tissues of host cell which may be to the detriment of the host • Disease-causing parasite

  24. Disease-causing parasites with an environmental stage • Entamoeba hystolytica • Environmental cyst stage • Causes diarrhea and dysentary • Naegleria • Free-living ameoba • Infects nasal passages of humans and invades brain tissues with potential fatal results

  25. Yellowstone National Park News Release STUDY SHOWS SOME YELLOWSTONE THERMAL WATERS CONTAIN AMOEBIC PATHOGENS July 03, 2003 - PR 03-46 Yellowstone National Park Superintendent Suzanne Lewis announced today that a recent study done at the request of the National Park Service shows that some thermal waters in the park, including the popular soaking spot Boiling River, contain the thermophilic amoeba, Naegleria fowleri and the bacterium Legionella.

  26. Tissue Parasite: Cyrptosporidium parvum • Has complicated life cycle • oocyst: environmental stage, metabolically dormant, survival stage • oocyst stores 4 sporozoites, each with infective capability • tropozoite is the intracellular form • schizont produces 8 progeny called merozoites • merozoites burst cell and infect neighboring cells

  27. Oocysts released in feces into environment Infectious oocysts ingested Sporozoites released Individual sporozoites infect cells Unhealthy environment Tropozoite forms Merozoites burst cell, form zygotes (oocysts), enter intestines Tropozoite transforms into schizont

  28. Adaptations • Able to withstand periods without water that is normally required for metabolic activity through cyst formation. • Cysts can be easily disseminated through the environment • Cysts withstand high temps, freezing, high and low pH • Question: Explain the advantage to the organism and public health significance of the cyst stage.

  29. Summary • Environmental microbiology covers a broad spectrum of environments and microbes • Health of the environment directly impacts the health of humans living in the environment • Environmental microbiology is experiencing a high level of visibility in our society today • Degradation of oil in Gulf of Mexico (image above) • Spread of West Nile virus across North America

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