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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)
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
Fluorescence
stains
Efflux pump
activity
Syto 9 + EB
Membrane
potential
DiBAC 4
Glucose uptake
activity
2-NBDG
Membrane
permeability
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
Bosshard et al.,2009
Loss of membrane
integrity
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
References
Michael 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. Egli
Solar disinfection (SODIS) and subsequent dark storage of Salmonella
typhimurium and Shigella flexneri monitored by flow cytometry
Microbiology, 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.wat
er.cnn>
SODIS. “SODIS (short for Solar Water Disinfection)" <http://www.sodis.ch>