nicole chou may.11.2010
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Nicole Chou May.11.2010. Nicole Chou May.11.2010. Nicole Chou May.11.2010. Global Water Situation. Water Scarcity. Billion people have no access to an improved water supply and far more lack access to safe water. SODIS (Solar Water Disinfection). - PowerPoint PPT PresentationTRANSCRIPT
Nicole Chou May.11.2010
Nicole Chou May.11.2010
Nicole Chou May.11.2010
Global Water SituationWater Scarcity
Billion people have no access to an improved water supply and far more lack access to safe water.
SODIS (Solar Water Disinfection)SODIS is a low -cost simple household water treatment method . Expose drinking water in plastic bottle to sunlight for more than 6 hours.
Mainly use solar radiation (UVA specific) Synergistic effect will occur if water temperature rise above 50 oC
** A positive impact on health has been documented in several epidemiological field studies. For example, In India, where a total 40% of diarrhea diseases and 50% of severe diarrhea episodes were prevented by use of SODIS.
Purpose Of This Research
- To measure the effectiveness of SODIS By define the inactivation pattern of mechanisms. To define the ability of survive and repair damage
- To confirm that temperature is not predominant factor in the elimination of bacteria.
Materials and Methods
• Enteric Bacterium - Gram-negative rod shape bacteria. Includes - Eschericia coli (pathogenic strains) - Salmonella - Shigella - Transmission route: Fecal-oral route * E.coli K-12 MG1655 Cells. Stationary phase cells .
Materials and Methods
• Multi-parameter flow cytometry
Materials and Methods
• Fluorescence stain
Cellular functions Efflux pump activity
Membrane potential
Glucose uptake activity
Membrane permeability
Fluorescence stains
Syto 9 + EB DiBAC 4 2-NBDG Syto9 + PI
Results
• Culturability
Results
Aerobic incubation VS. Anaerobic Incubation
Results
Results
• Total [ATP]
Results
• Efflux pump activity
Results
• Membrane Potential (Depolarization)
Fig 5 d-f Fig 4 e
Results
• Membrane Integrity
Fig 5 g-i Fig 4 f
Results
• Glucose uptake ability
Results• Syto 9 vs. Culturability
Results• Syto 9 vs. Membrane potential (Fig 5e & h)
Discussion
• Inactivation Pattern
[ATP] decrease
Inactivation of Efflux pump
Loss of Culturability
Loss of membrane potential
Glucose uptake rate decrease
Loss of membrane integrityBosshard et al.,2009
Discussion
• Subsequent dark storage of Salmonella typhimurium
Bosshard et al.,2009
Discussion
• Subsequent dark storage of Shigella flexneri
Bosshard et al.,2009
Discussion
• Inactivation mechanism
• Rapidly [ATP] and inactivation of Efflux pump activity
Due to damaged on respiratory chain
PyKF (Pyruvate Kinase) is a direct target
Discussion
Repair and regrowth - Viability test were carry out 5 days after irradiation. No regrowth or recovery. Significant decrease in all measured cellular functions
** This indicates that damaged that caused by UVA light is irreversible.
**The re-grown of permeabilized cells has never been shown
Conclusion
• SODIS and artificial UVA light kill enteric bacteria by inactivation of the respiratory chain and subsequent exhaustion of ATP.
• Split exposure reduce the light dose required for inactivation.
• Temperature is not a predominant factor in the SODIS method.
SODIS Demonstration
ReferencesMichael Berney, Hans-Ulrich Weilenmann, and Thomas Egli Flow-cytometric study of vital cellular functions in Escherichia coli during solar disinfection (SODIS) Microbiology, Jun 2006; 152: 1719 - 1729.
F. Bosshard, M. Berney, M. Scheifele, H.-U. Weilenmann, and T. EgliSolar disinfection (SODIS) and subsequent dark storage of Salmonella typhimurium and Shigella flexneri monitored by flow cytometryMicrobiology, April 1, 2009; 155(4): 1310 - 1317.
Kenya Sun Water Safer to Drink CNN. David McKenzie. September 1, 2009 <http://edition.cnn.com/video/?/video/world/2009/09/01/mckenzie.sun.water.cnn>
SODIS. “SODIS (short for Solar Water Disinfection)" <http://www.sodis.ch>