Pathogens in Air and Aquatic Environments

1. Pathogens in Air and Aquatic Environments

3. Environments: intercontinental dispersal of dust

4. How much dust is moving around?

5. How much dust is moving around?

6. Movements of Dust

7. Airborne plant pathogens: soybean rust Caused by a fungus. Spores are airborne

8. Airborne citrus diseases

9. Pathogens in space 234 microbial species were identified on Mir after 15 years in orbit 108 bacterial species, 126 fungal The greatest diversity of “technophylic” fungi (eat polymers, corrode metals) Evidence of multispecies biofilm on decorative surfaces

10. Factors that affect survival of pathogens in the air Atmosphere is inhospitable to microbes UV, dessication, free radicals

11. UV-induced damage

12. Most airborne pathogens have mechanisms to resist UV, dessication spore formation pigments

13. Survival of Bacillus spores

14. Survival of Bacillus spores

15. Aquatic Environments Eutrophic nutrient rich typically shallow, warm Oligotrophic low productivity, nutrient-poor

16. Plankton Phytoplankton = primary producers (CO2 + solar energy --> carbohydrates)

17. Marine Environments

18. the Ocean Photic zone light can penetrate 200m down in clear water 1m in turbid coastal zones Aphotic zone No light Neuston air-water interface Pelagic zone water column, planktonic habitat Upper part is epilagic zone = photic zone Benthopelagic zone sea-sediment interface

19. Aquatic Environments Benthic = interface between water column and mineral sub-surface Lentic = standing water Lotic = runnic water

20. Benthic habitat Benthos = a transition zone between water column and mineral subsurface Rich in organic matter and life forms benthic life forms include enteric viruses, which were detected for up to 17 mo after dumping

21. Microbial mats

22. Pathogens in Aquatic Environments Sources: run-off shedding from animals humans (directly) many are normal aquatic microloflora, opportunistic pathoges Factors influencing survival Die-off varying oxygen concentration, pH, UV predation by amoeba, phages, predatory bacteria

23. Just how many of them are there?

24. Viruses in Aquatic Environments Survive in shellfish Are carried by currents Viruses can move 2 mph (in one study up to 141 mph(?) Environmental conditions affect survival Reoviruses (and other viruses) are only found during cooler months. Why? HAV, enteroviruses, Norwalk-type viruses are detected in oyster beds after rains, and coincide with human outbreaks Survive better in cooler temps (22C vs 33C), based on studies in the Keys

25. Survival of pathogens in aquatic environments Viable, non-culturable state culturable counts decrease, bacteria are visible microscope, nucleic acids are detectable respond to influx of DOM Synthesis of new macromolecules ~ to the break down “dwarf cells”, “round cells”

26. Survival of pathogens in aquatic environments Viable, non-culturable state culturable counts decrease, bacteria are visible microscope, nucleic acids are detectable respond to influx of DOM Synthesis of new macromolecules ~ to the break down “round cells”

27. Plankton: free ride for the pathogens Using DNA probes and staining, Binsztein et al (2004) detected V. cholerae on phyto- and zooplankton, and in water. Many V. cholerae cells were VBNC

28. Plankton-associated human pathogensMagueri et al., 2004

29. Zooplankton:bacteria eat it and develop appetite for humans Chitin - one of the most abundant C sources in the ocean V. cholerae can grow on chitin as a sole C-source V. cholerae has chitin-binding proteins on its surface Human epithelial proteins are decorated with chitin monomers

30. Aquatic Environments: sushi sampler special for Salmonella 4% are of human faecal origin, 20% are native bacteria and viruses 80% of mussels tested positive for at least one of the following: Salmonella, Clostridium, E.coli-O157, Plesiomonas, Vibrio spp. California study. Miller et al., 2006 Compared to other foods, seafood is still relatively safe!

31. V. vulnificus

32. Biotic and abiotic pressures in aquatic environments and air